Hi all very new to this so not sure what to expect.
My partner and I have been together for 18 months. When we met we had both been single for 5 years me living with my 6 year old son and him living alone but having his 2 children on weekend, this meant he had all the free time to himself and come to see me as and when it suited us both and he loves his gaming so he could do that whenever he wanted to.
Within 4 months we were meeting the kids in a relationship and falling pregnant. Everything was fine he was hands on with the older kids we had between us anyway, was amazing through my pregnancy and really put me on a pedestal with how lucky he was to have me.
Baby is now 5 months old, he's very hands on, helps with feeds, has him when I want to bond with my son, plays with him when he's home from work - however partner is beyond stressed, so when baby cries he comes back to me and gives up trying to soothe him. I suggest meeting friends or going the gym there's always an excuse as to why this isn't practical. We don't have sex any more despite being late 20s and despite my not so subtle digs.
We've had the normal bickering about this latest one being last night where he confessed 'This life isn't for him' now I know he loves me we cuddle up in the sofa and watch films together ( when I can surgically remove him from his game) etc and he tells me he loves me. However i don't know where to go from here.
' He loves me but doesn't know if he wants to be here, he's not patient like me, the kids stress him out, I stress him out with the sex situation, he just wants to relax and play his game, but doesn't want to leave'
I fear that he hasn't adjusted from being a single man being able to sit on his game till early hours to living full time with children and having to balance that out he feels he should be able to spend his free time as he wants - I don't see how he has free time because I sure as hell don't 
It's very long and I'm probably missing out crucial facts but I just need advice before a family is ruined which is where I fear this is heading.
Any help or advice is appreciated thank you. Xx