I really like this guy, but he is still with girlfriend

K so I used to work for a movie theater when I was in high school, and I had a huge crush on this guy…lets call him s. So we would always flirt together and stuff. But then I found out he had a girl friend so I knew he was off limits so we would just hang out as friends. So I ended up quitting my job at the theater and shortly after so did he I was out of contact with him for awhile we would always see each other at this yearly comic book convention I always go to. I decided to be friendly and just chat with him casually, a few days after he went drinking with mutual friend. She told me apparently he got really drunk, and he was saying how he and his girlfriend are having problems…and that he really liked talking to me the other day and that he wishes he could see me more cause he has a crush on me. So after my friend told me this I started seeing him and hanging out with him more..we gone to few movies and out for dinner, but its been just as friends. I would always invite him out to concerts and stuff but he is like always super bissy working. So I havnt talked to him in awhile and one day he randomly calls me out of the blue and was like I feel bad for not being able to come out to any shows, can we chill this weekend. So we made plans but they got canceled again. I really like this guy, but he is still with girlfriend, but I know he likes me … I think he might be scared since hes 25 and im still only 19…what should I do??