Boyfriend acts like he dont want to have anymore?

We have been together 8 years, I dont think hes cheating, he never ignore my calls, if hes gone hes where he says hes at(i call the the friend he says he guna be with and he gets on the phone) never hides his phone, no signs of cheating at all. I got preg and around between 6-8 mnths he seems less interested, my son is 4 mnths now and its still the same, i didnt gain weight i actually lost i weighed 148 be4 preg and now i weigh 114 i kno he likes me weighing less so i dnt think thats it(i had gestational diebeties so i lost and plus i had gall stones so that made me loose a ton cuz i couldn't eat i dont look so skinny its nasty im short and still got meat on me so im not skin and bone, i weighed 100 when i met him) he wanted to have everyday untill i hit about 6 mnths preggo..iv been having dreams of him cheating on me but i really dont think thats it..what do u think?? any ideas??? I kno he hates condoms and i havent got on birth control yet so i was thinking sence we have to use condoms right now maybe that was it..idk..seriouse answers only please.