Emotional Incest and Mama's Boy is the same thing. It's a man who is enmeshed with his mother and has difficulty being emotionally independent. Most likely she stifled that independence and what he felt was "closeness" was really enmeshment.

My father died 3 years ago and while I do sometimes tear up thinking about him, most of that intense grief has passed. I miss him, but life goes on.

Even if it were the spouse, five years is way too long for this level of grief. Therapist needed. For him and for premarital couples counseling.

Do not marry until he gets some therapy and his drinking under control. One partner medicating with liquor is a huge red flag for a relationship. 

After i found out i was pregnant and she was excited to be getting a grandchild...

i had to deal with hormones and coroner making issues with releasing mums body because hospital dr effed up issuing a death cert as in our religion we bury the dead within 24 hrs and they know this but its common for them to make bs reasons to suit their coroner inquiry quotas.

i was upset but i had my husband. When it was time to give birth to both my kids, its just my husband whom i wanted. My life didn’t revolve around my mum etc...

that said many people grieve in their own ways and what may be quick for others is a much longer time for others but i think this man has not learnt adequate coping mechanisms for mourning 

... men enmeshed with female family members at the expense of their wives. And make no mistake, you are paying for your husband's lack of boundaries.

You say, "Maybe a therapist could help me figure out why he was so needy of his mom." This is a bit confusing. Who would be the therapist's client here? You or your husband? If your husband, figuring this out is not actually in your wheelhouse. He's a big boy and it's his business to hash out (or not, and after 5 years it sounds like he much prefers "not').

If you are proposing yourself as the client, you are likely to be told (in tactful therapy terms) that it doesn't really matter to you what his issue is. YOUR issue is getting him to behave in some acceptable fashion, which he clearly is not doing.

Good luck. I was married to a mama's boy for way too many years. They never get past it.

First rule of any successful marriage (okay, not first, but top 3) is that you can't be tight-lipped about something that is negatively impacting you and the relationship. Respect for the dead means you don't piss on her grave or purposefully make fun of the hairstyle she had when she was alive. Respect for the dead doesn't mean you don't point out how the grief someone is experiencing, or the issues that person had with said dead person that are still impacting them today, is toxic to the living. Someone dying doesn't mean their entire life gets boxed and wrapped in a bow, where only the good things about them can ever be unpacked.

So, now that we've determined that it's NOT disrespectful to bring this up to your fiance because you are 1) not speaking ill of the dead, and 2) he is acting in such a way that is detrimental to your relationship (I mean, random bouts of drinking heavily because of his five year's dead mother that drives you to a stepparent forum because we're likely the only folks who won't tell you that you're crazy is a gnarly big red flag), what do you do?

First, I'd recommend individual counseling for you, but not to figure out what is wrong with your FH. It's to figure out why you think he is a great man WHILE ALSO recognizing that he doesn't have the emotional maturity to handle tough situations without resorting to alcohol-fueld nostalgia trips. This isn't as simple as "oh, he's just sad". This is a man who hasn't learned how to grieve in five years, who medicates at the expense of his physical health, and deals with his grief in such a way that makes you feel jealous and less than.

WHY are you okay with that?

WHY are you the one actively using Google to figure out how to fix your relationship? Why doesn't he recognize what he's doing is detrimental? Why does he get a pass?

This leads me to the second thing you need to do. You need to talk to him about this. I'd work with your therapist to figure out how would be best to approach this. I'm a "let's just throw it all out there in a conversation" kind of person. You might do better at letter writing. Part of what your counselor can help you with is developing a communication style that effectively delivers your message. And make no mistake: your FH needs to hear that his actions are troubling.

And I'm going to close on why this is such a problem that needs to be worked through and why you need to NOT get married or have kids with him prior to sorting this out. Incestuous relationships are rarely ever mutually consensual, and cannot be consensual ever between family members who are of different familial hierarchies, such as a son and mother. Some amount of grooming has to take place by the parent to make the child feel comfortable with stepping over parent-child boundaries. That grooming that erases boundaries causes emotional harm to kids, in a way where they may never feel like a victim because they were never physically assaulted/molested by their parent, but will exhibit the same responses to trauma as those who we recognize as what we see as "traditional" victims of incest who have physical relations with their parent.

Your FH hasn't even processed his grief from losing his mother, which means he hasn't processed what happened in his relationship with her. The drinking would be a sign, to me, that he knows something was wrong with that relationships and he's trying to numb it versus face it. While you may be able to marry him and deal with it, any future children you may have are at risk of him perpetuating the incestuous cycle that started for him. I don't mean to come off as saying "all victims will become abusers" because that's not true. However, your FH is showing you that he hasn't grappled with this and has no intention of grappling with it on his own. THAT is the red flag. THAT is what makes him more likely to continue the cycle versus break it. He may not even realize that there is a problem, which means he may slip into unhealthy and detrimental parenting without realizing he's being harmful.

Do I think you need to run? No. I do think you need to pump the brakes, though, and work through this. Incest isn't some light topic that just makes a family "quirky". It HAS to be addressed. The questions you have to ask yourself are whether you want to stick around to help "fix" your FH, and if you do, what does the end result need to be for you to remain in a relationship with him? And never say "we'll get through anything together" because it's not true. It's a fallacy we tell ourselves so we don't do the hard work upfront, hoping and praying it'll be okay, and 9 times out of 10 we're worse off than if we just did the hard work upfront - and that may mean ending a relationship we wanted.

Best of luck to you.

Everyone grieves differently. My father passed away completely unexpectedly a little over 9 months ago. For the first few months, I was not myself. It was like a weird out of body experience. I went back to work after a week and two days, but I was like a zombie at work. I would completely lose it as soon as I got in the car to drive home, because I had spent all day trying not to cry. Looking back, it was not safe. I almost got into a couple of car accidents because I was crying so hard. I used to talk to my dad every day...sometimes twice a day, so we were close, but we had a normal father-daughter relationship. We didn't dress up for one another and we were not overly enmeshed. I don't even know if I'd describe myself as a daddy's girl and we weren't as close when I was a child as we were in recent years. I still cry on a fairly regular basis over losing him and I still feel anxiety about things happening to other family members, because his death came out of the blue and should not have happened (long story short, several doctors made a mistake). However, I can also think about him and smile or even laugh. I sincerely hope that I will not feel the same way five years from now. I know I will miss him terribly, but I also know that the pain will continue to lessen. My DH lost his father - also unexpectedly - over 20 years ago. He was also very close with his father. He tells a lot of stories about his dad and talks about him all the time, but neither one of his siblings do and MIL rarely does. It bothers DH, but I remind him that everyone grieves differently. 

I'm sure you know this, but therapy is not for "crazy people". Your SO is struggling to deal with a loss...that's normal and sometimes you can get stuck in your grief. Therapy can help you to get unstuck and help you remove your need for unhealthy coping mechanisms, like alcohol. I had been seeing a counselor when my father passed - thanks to BM's and MIL's craziness - so, that really helped. 

If you see it, it is there.

I would introduce  your DH to a therapist who can help him work through his mommy issues.

Whether he would admit it or not, his mommy crap has detrimental impact on his life and marriage.  And as importantly, it impacts his own children and their adult parental relationships.

I am very close to my own parents.  However, I do not allow my relationships with my parents to be a detriment to my life, marriage and relationship with my kid. If I did, my parents would be the first people to apply their collective foot to my butt to force my head out of my own ass.  It is sad to me that your MIL ruined her son rather than raising to be independent and confident out from under her skirts.

Your MIL created a victim and not the source of unconditional love she was likely looking for once her marriage imploded.  She was evil and she did her son no favors. She created a victim.  That your DH does not have the adult confidence to see that is a firm indicator of how successful his manipulative mommy was at turning her son into her incestuous minion.

IMHO of course.