He assures me that he can handle it and that it will never be my problem

If this ^^^^ were true, it wouldn't be a problem, now, as she wouldn't be frequently voicing that she resents your relationship, but he evidently allows it. She obviously has no respect for her dad (or anyone, it sounds like). I doubt that is a new thing and I doubt her behavior will change any time soon.

She sounds hell bent on making his life miserable so unless he is willing to cut her completely out, I don't see how he's going to keep it out of your and your kids' world.

Read up on this site and you will see how men let their kids affect their relationships. Whether they have good intentions or not, most are not willing to put their offspring in their place. They are more worried about fall out from their kids than they are their partner.

Frankly, if you are not seeing him DOING anything about it yet, and he should be, I doubt he will do much about it in the future, he will figure if you've put up with it so far....  Or, he will tell you, "Hey, you knew what you signed up for!" Well, you are seeing what you are signing up for, don't bet on that to change.

Just my opinion, but I think troubled skids aren’t easily solved, they get that way because of their troubled childhood, and because they have troubled parents.  Some of it might just be genetic predisposition, why one kid does well, but the other does not.  Either way this kid is at the point where someone is going to have to convince her to change herself.  

If you’re planning to continue seeing this guy, I would not take his word that he will solve it, he obviously didn’t take steps to do it when she was a toddler, when it’s much easier.  You need to make it clear that you expect that his daughter be kept away from you for your own mental health. 

And mostly when grand skids came along. My SS wife is controlling andf very close to BM. Thats when it all started. . I would not be with him had I had any indication.

"Was anyone proactive about addressing skid issues before the relationship got too far down the road?"  No and I have paid a price.  Before we got married I didn't see much of SD but when I did she was OK.  Once we got married everything changed.

I don't know if Steptalk was around 28 years ago when we married but if it had been I probably would have never married DH.  You mentioned visiting a counselor before the wedding.  Very good idea.  If you read some of the posts on here you will learn what questions you should ask and take a long hard look at the red flags.  Before I got married I had this rosy picture of the blended family and a husband who placed me as his top priority.  Believe me - there were all sorts of read flags I chose to ignore, and was too afraid to deal with them when I found out the truth.  Today I kick myself in the butt at least once a day for being so stupid.

If this man can not straighten his daughter out in front of you and show you that you ARE his top priority NOW, run like hell!

Never date a man with a daughter! I tell all my single girlfriends that. Read more on this forum. There may be some success stories, so call me jaded, but seriously you are dating and having this much trouble. Dating should be fun, enjoyable, not considering counselling. Is he worth this effort? If so, go for it. BUT If she doesnt like you now, chances are the more serious you get, she will amp it up. 

In all sincerity best of luck!

Welcome to the posting world, Hesitant. Ill give you my experiences, unless you have already read my blogs, my long and dreary blogs. Im sort of the middle road type. Ill give my experience, rather than advice, here.

I met my then SO-now-DH 6.5 years ago. It was his first time out after his separation from a very high conflict BM I call Toxic Troll. He has 2 children, SD13 Munchkin and SD20 Feral Forger.

Munchkin is sweet, and caring and most of the time I think she truly appreciates me. I do love her dearly, and she is really good company so we have lots of "adventures" together. Or we just stay home and binge watch something we both agree on. I met her when she was 8.5, and we really bonded well, however I need to constantly remind myself that "I am not her mom".

Feral Forger is her opposite. When a teen she was sullen, filthy, rude and mean. She started stealing, and thankfully was caught before too much damage occurred, and unfortuneately not punished at all. Complicated reasons. She graduated high school (barely), stayed with us full time, and got a job a few towns over at a chain restaurant. She is still working there, is actually still parttime and no drivers license. DH had promised her a car upon graduation but she needed to have a license first and a job to pay for insurance.

A few months after graduation, she ghosted all of us, with no context or reasons. There were no arguments, no one was kicked out. Just ghosted us. Not even her younger sister heard anything. November of last year, when she was 19, she moved in with momee, Toxic Troll, and poor munchkin, who was going to take over the other room in the small shabby apartment, was again booted to the couch. Feral Forger pays $200 monthly. Well, as time went on, the drama grew. She is a filthy pig, as I mentioned (sorry- no offense to pigs!) and her mother had a very tough time trying to get her to clean. So, like the stunted teenager-20-year old that she is, would accuse momeee of abuse, and go on massive tirades putting munchkin in the middle, because momee would block her, just on and on. Tirades that included threats of suicide and accusations of drug abuse, etc.

During one of these arguments over cleaning (and then rent also), Feral Forger would ask Dadee for $$$. He gave her $100, and then she asked to move back in, and "could she have her old room back, please dadee put YOUR CHILD  ahead of your stupid wife for once."

Wow, with a plea like that that, all charming and such, how could he refuse? He told her that nothing has changed and didnt she just accuse him of abuse? If he was so horrible, if CLove the "stupid wife" was so horrible, why would she want to live with us again? Crickets. He told her to lose his number he was tired of the drama.

That is where we are now. She is no contact with us, she is on a 30-day notice with Toxic Troll and we dont know the future of things. No license, only works parttime and she takes shots of whiskey to wash down her xanax and posts nice videos online of her smoking pot and vapng.

She could definitely use some therapy. Oh! Wait! She DID go to therapy, and was told she has sociopathic tendencies. Well, pardner, thank ee fer the info! I called that a long time ago when I found steptalk. She is a sociopathic liar with Narcissistic personality disorder. Heck with the anxiety, lets focus on the good stuff. So, she is a  mess, and right NOW I dont have to deal with it.

I have turned her old room into an oasis with plants cascading the windowsill, on all the tables and a fish tank bubbling with my Koi. I watch sunsets there in the evening because I can. There is no "coming home" going to happen for Feral Forger, because guess what? My mother owns the house, and we will buy it from her soon, ergo, the decision really isnt DH's to make.

Oh, and you wonder why Feral Forger has that monker? She recently stole checks and credit cards from momee and drew out cash and now is in trouble with mommeeeeeee.

Sorry so long, hope this gives some perspective.

He has not handled it before you came along so what makes you think he will handle it now that you are in the picture?  It sounds to me that he is telling you in not quite direct words that it isn't any of your business.

It is completely your business as long as  you are in a relationship with him.

My XW and I did pre marriage classes through her church (Catholic).  Sadly that did little to address her lack of character, cheating, etc......  Had I known ahead of time that she was a cavern crotched adulterous whore I would not have married her.

You know ahead of time that your SO is a failed parent regarding his youngest.

Make your decisions accordingly.

Good luck.

You are 6 months in.  If you are having this level of problems now then he is not the person for you.  You don't "make it work" with someone with whom you have no investment.  You were married before - my condolences on the loss of you husband - so you know the nature of commitment.  This is way too early to be truly committed to anything long term regardless of how much you may want it.  I am sure that you are lonely and this is probably a very nice man but he has baggage that he needs to deal with before he is able to be available for a relationship.  He created the problem and he needs to fix it.  Once he has done that, if you have not been snapped up by another nice man, he will still have your phone number.

Do you really want to sign on for this drama for the rest of your life, or at least the rest of your possible husband's life?

I hate to say this but unless he's actually doing something about this now, he won't change.  Trust me.  Why isn't he addressing the problem now?  You mentioned he said his daughters behaviour will never be your problem.  Unless you intend to be invisible in the future.....it clearly will become your problem.  Good luck with counselling, we tried.  DH agreed with everything the counsellor said, then did nothing to address his adult kids shitty behaviour.  We are now in a REALLY bad place.  I am not criticizing you by the way but HE WILL NOT CHANGE.  I wish I'd walked away after 6 months.  You have the opportunity to do so.....

I hate to say this but unless he's actually doing something about this now, he won't change.  Trust me.  Why isn't he addressing the problem now?  You mentioned he said his daughters behaviour will never be your problem.  Unless you intend to be invisible in the future.....it clearly will become your problem.  Good luck with counselling, we tried.  DH agreed with everything the counsellor said, then did nothing to address his adult kids shitty behaviour.  We are now in a REALLY bad place.  I am not criticizing you by the way but HE WILL NOT CHANGE.  I wish I'd walked away after 6 months.  You have the opportunity to do so.....

Yes that's true, no one of them didn't change .... I had such experience in the past with my ex-wife and it was horrible, thanks to my friend and my family which helped me and supported me. I was in depression a few years ago and my friend advised me to use some dating apps or sites, just to relax and forget about my ex and it actually helped me a lot, so now I don't even care about her, even more, now I use a great adult dating site :https://shagbook.com , which helped me to overcome my depression, that's why I recommend it to you, maybe you'll find there your beloved person how did my few friends or at least will have opportunity to relax a bit.