Does he still like me? Why is he doing this?

Ok so my ex boyfriend, from about a year ago, and I are neighbors. So we see a lot of eachother becuase everyone in my neighborhood is close friends. Last summer is when we went out off and on. Now that it is summer again, we see even more of eachother, especially at night at parties or when we play manhunt outside at night. So last night he was on my team for manhunt and we ended up getting seperated from the rest of the group. When we were hiding behind this tent, he kept sitting really close to me and touching me and stuff. Then we decided to leave the tent. I was barefoot and there was a lot of rocks and so I was like "Oww this hurts" and then he said "Come here" and so I turned around and walked back to him and he picked me up and carried me through all the rocks... And then we had to lay down in the gr right next to eachother and he kept putting his arm around me and holding me and stuff... But the thing is... He has a girlfriend. Him and his girlfriend are really touchy feely but supposedly she is mad at him because some other girl was flirting with him and he didnt tell her to stop or something. But he said that he didn't really care that she was mad at him. I don't know what to think! Should I keep flirting with him and talking to him and stuff or should I lay off and tell him that he should stay with his girlfriend and not me. I like him. I do. But it sort of ends up like this every summer because we dont see that much of eachother because he is a grade younger than me, but a month older because I started early. We see a ton of eachother over the summer and then like none during school so we end up dating over the summer but then breaking up before school. It's kinda annoying because I really want to have a long term relationship with him. We have known eachother for about 6 years now. I barely know his girlfriend too so if that matters. Oh and I am going into 9th grade and am 13 years old and he is going into 8th grade and is also 13 years old. What should I do help me pleaseee ):