I think this guy but i dont know if he likes me.?

So theres this guy and we talk on the phone for hours and hours and he has a girlfriend but he CONSTINLY flirts with me and i mean i like him ALOT and he snuck out to come see me at 3 in the morning. He tells me he loves me somtimes and hes 15 and iam 13 and i really want him he complimeants me all the time and he even hugs me from behind and were "cuddle buddies" but we never cuddle and on my birthday he bought me a necklace and i just dont know if he wants a realationship. and i dont want to ask him out cuz i dont want to be a homewreker and break hm and his girlfriend up.. Wat should i do..?