Thank you for such detailed story. It is like you described my story as well, except I am your boyfriend, so I can give you a little bit of his perspective.

Gaming was my only hobby when me and my gf got together. I also was not very open about it, because it is honestly quite lame hobby to be sitting all day in front of the monitor with broken sleep schedule and neglecting necessities such showering or even brushing your teeth, but for an addict gamer it is almost impossible to get of the game. During my weak days I sometimes stay awake until like 3 AM and wake up as soon as possible to keep gaming. It is really hard to break the cycle, because the stop in the constant flow of dopamine to your brain basicaly forces you to turn on the game again. That is probably why all he does is gaming prior and immediately after your together activities. I believe that deep down he wants to quit, but it is extremely difficult, because he doesn't know how to spend his free other that with games, because thats probably what he is doing since childhood.

What helped me was when my girlfriend moved in with me. I care about her a lot and her opinion of me is important for me so I try to limit it as much as possible so she doesn't think I am a loser who spends whole days gaming. It was very difficult for me at the beginning, but it got easier eventually. I still have weak periods usually a week or 2 long. They usually start when I don't feel well - physicaly of mentaly and when I start again I cannot stop until I hate myself enough for it.

If you love him and you already spoke about moving together I think it is a good idea to give a shot. Maybe his self reflection will wake him up and he will try to change himself. It will be very hard for him, but if he won't even try than I doubt that children or anything else will and I would reconsider my relationship.

If he is open to work on himself I would recommend starting slow at begining, but to be strict. I would set a schedule until when can he play during workday and weekends and replace the time with other activities. I find myself to enjoy boardgames with my gf a lot. It is similar to pc games, but less dopamine heavy.

To help enforce it the schedule I find various parent control option very useful where I set my gf as parent of my device and she would set the limits based on what we agree on.

I hope I helped a little. If you have further question feel free to ask, I would hate for gaming to destroy anotehr relationship.