It is normal! Why should you have to settle for being happy only 50% of the time? (You shouldn't!)

What are some of the differences in dynamics? Have you tried talking to your wife about it? 

With her you are happy. Being the only adult in the home who consistently enforces the rules, you are not happy.  Tell her what you need from her and hold her accountable for delivering.  

A 13 year old girl and a 16 year old boy are the cusp of "big problem" years. (AKA "Little kids give little problems, big kids give big problems.")  Imagine drugs, drunk driving/crashes, pregnancy, etc. 

This is why it is imperative that you sit down your DW and kindly explain to her that you are unhappy and the two of you must undergo marriage counseling, get on the same page about how skids behave while in your household, and how she needs to follow through with discipline for them.

Keep in mind that these kids are for life. Even if they launch successfully there are no guarantees they will launch for good. It is not unheard of for many adult offspring to still be depending on parents well into their 30s. Or then come the skids' partners/grandskids and related issues. 

Just be realistic that this isn't just the tough teen years - it goes on for life. Take it from one who knows.  

Skids turning 18 don't mean Jack Crap except they get WAY more expensive!!  Unless your wife is capable of ruling her roost - you are in for Hell on Earth 24/7!!  It's pathetic to be so negative but, friend, my SD's are both in their 50's and refuse to freakin' face reality.  Life is short, the older you get the faster it goes - take a good long look at your life and you'll know if your situation is worth the sacrifice.  This site is the best crystal ball you'll ever get to look into - only you can determine your future.

My take is a little different than some of the others here. You say you are disengaged but then you say that you still tell them to clean their rooms and do chores? I think you need to back way off. I understand that messes in common living spaces have to be addressed by why are you telling SK's to clean their room? That's not being disengaged. Just keep their bedroom doors closed. Teens will be teens, it's a rare teen that is super tidy. In our house it's my job to parent my BK's and it's DH's job to parent SK's. Either we get our own respective BK to clean up after themselves OR we clean up our own BK's mess. I would never expect my DH to deal with my BK's messes and vise versa. Sometimes we help one another but it's because we want to, no obligation. One of the main ways that I "help" DH is by gathering up whatever personal belongings SD left out, put it in her room, close door. Kid's messes are rarely a point of contention for us. In our case the kids all launched after high school so it was a temporary problem. It would be a different story if they were failure to launch kids.

Just curious because some of this is relatable depending upon experience.

I am also speaking from a place of rethinking the entire kid / step-kid scenario.  

In stating this above, I grew up in 2 step scenarios.  My own dad died when I was a child, my mom remarried the first time to a seriously OCD crazy guy with 2 kids and he moved into our house. The 2 kids visited on Sunday only every other week.  We were  still experiencing the death of our dad we accepted him but not all of his crazy rules on our household.  Eventually Mom divorced him and went on to marry another guy some years later with adult children who had a lot of issues and so did he with parenting.  In watching my mom for years I said to myself and anyone who would listen, I would never get into that and marry a guy that I didn't like his children or who had ad crazy children.  It will never work.  

So fast forward.  After a brief marriage and children I raise completely on my own, I meet and remarry.  I quickly learn that I have in fact copied my mothers life and I am pretty much in the same situation that I said I would never be in.  How did I get here?  Clouded by "love" of my DH and hope that the SK's will turn 18 and someday go away. 

Moral to the the story..... THEY ARE HIS CHILDREN THEY ARE NEVER GOING AWAY!!!!!!!!!!!!!! Read that again front words and back wards and you shouldn't be in a relationship where that is what you want!!! Me included.  I always said and still believe that the only way it will work is if ALL kids in the scenario are treated equally and I may have lost that at a point but still believe that.  I think you need to ask yourself how you would act and react if they were your kids and start from that point.  

I truly think, me included that we are a little harder on the steps because we don't have that love for them.  I think if all parents involved are open to each parents involvement step and biological it works easier but that is rarely the case so I think that most step situations are very challenging.  I have been rethinking mine a lot lately and what I could have done differently. There is a definite separateness between me and my SK's.  But I went in with a different mindset until I learned of BM's crazy personalty disorder. She ran the show because everyone was worried to set her off.  I think if I had it to do over again I would have not tolerated her craziness and put my foot down to DH or walked!!

It is hard but my advice would be to talk to her without accusation and from a place of what is best for the kids and that you care how they grow up and the world will not be kind to them if they can not care for themselves.  

I have been with DH for going on 12 years... you need to learn to disengage... DON'T enforce rules your wife isn't willing to. leave it up to HER to say something, and if she doesn't, thats on her.

The "rule" might be that the kids move out and are on their own at 18, but that doesn't mean that is what will actually happen. Adult kids bring a whole different set of problems. From what you say, it doesn't sound like your wife's kids will even be capable of being independent at 18. Are they learning life skills? Spend some time reading the Adult Stepkids forum here and see what you might be in for. I think you're fooling yourself that this ends at 18.

You need to have the "I'm happy only half the time" conversation with your wife. She might cry. But that doesn't mean you shouldn't be honest with her. Thus far, she hasn't been willing, or maybe capable, of holding her kids accountable to house standards. How about involving a third party therapist to sort through this? Maybe your standards are set too high for teens. Maybe your wife needs some tools to be able to address her slobby kids. Maybe you need to disengage more than you already have. I don't know the answer, but living in limbo as you are is surely not healthy for you or for your marriage.