Why is he doing this!!!

Hey guys..a lot of my questions are about love and relationships for some reason lol but this has been a ongoing problem that I can’t seem to figure out. Ok I dated a guy when I was 19..we didn’t work because I was away at school..but when we were together things were good and he was like I was the type he would marry or whatever but I didn’t take it seriously lol..well after we broke up he got back with the mother of his child..but we were still talking and hanging out or whatever every now and then but then we just stopped talking after a while..he contacted me out the blue one day every since then he would call me every few months to check on me and see how I am..he never wants sex or anything he just checks on me or just wants to see me..and when he does see me sometimes he just looks into my eyes or he’ll hold my hand or try to kiss me which he barely did when we were together or just tries to make sure I’m happy.. But never tries sex (unless I want to lol)…sometimes him calling me will go on everyday for about a month and then itll stop for a few months then he’ll do it again..this has been going on since we broke up which was 4 years ago when I was 19 …I’ve been there through all of his girlfriends he’s had after me that I know of…the last time I hung out with him which was in january of this year he told me he had a girl and that she was pregnant..and we talked about a lot of things that he never told me before about his mom and family and just pouring out his heart to me which he never really did when we were together 4 years ago…someone please try to explain why he is doing this…