My boyfriend says he loves me and wants to be with me, but how do i truly know?

My boyfriend and I have been together for 4 yrs in August. He broke up with me after 3 yrs for like 2 mnths and was seeing this other girl for a month or so after breaking up with me. They seemed like they were in love. I asked him if he still has feelings for her and he says thats done and over with. The first 2 1/2 years of our relationship was absoultly magical. The last 2 years was a little differnt. He doest really show his affection toward me as much as he used to. When him and Julia were together he was how he was with me, with her. He said she awakens something in him that has been dead. (This was after we broke up) i quess what iam worried about is the fact that he says he loves me, but he doesnt show me as much affection as he used to in the beggining. I am happy with him, and from what i understand hes happy with me, but iam just always wondering if he is wanting to be with Julia or if he really wants to be with me. Sometimes i think hes stressed and that it will get better.