How do you know if your partner has lost that in love feeling w/ you?

We were ok before when we first moved in. It was like he knew i was the one he wanted to be with for the rest of his life. We moved in together and i was working like crazy, he was getting few hours. He cleaned, cooked, was more active with my son b/c he was watching him while i was working. I know i am not the easist person to deal with at times, but i was tired and he wouldnt give me some space when i would get home from work, so at times i may have taken it out on him. I felt like i was working like crazy and he was reaping the rewards. Then he got more hours, got more money, went out more, and one night him going out and coming home, a arguement occured about him going out, and he picked up the phone and called a girl in front of me. Well that girl is no longer in the picture, but it was like he just stopped being there for me, while i was still trying to be there for him. He now doesnt go out anymore, like he did before at least w/ girls that i knew he went w/. But not really helping around the home, he watches my son and disciplines him, but mainly sleeps, eats, and potties. I love him a lot, but i dont know if he is trying to break up, (which he says he is not, says he loves me and wants to get married) or he just really tired out from all the working and needs some more alone time now adays to recoup. Or is he there just because and fell out of love. He is 28, im 29 w/ a son. I take care of most of the responsibilities. The other night he told me he loves me to death and wants to be with me. When he feels nervous, or afraid, and just cant sleep he says he thinks of me, and it calms him down b/c he knows w/ me everything will be ok.