Having a Blesser?

I met this guy at the mall when I was with my friends and I waved at him when he drove past cause I liked his car. Long story short he bought my friends and I drinks and food that night and we exchanged numbers. I liked the idea of someone spending money on me, and since he's 7 years older than I am (I'm 18) I refer to him as my blesser. I know those kind of relationships are a tit for tat, ever since we started spending more time together and got intimate I think I'm falling in love with him and he has a girlfriend but promises he doesn't love her as much as he loves me. What advice can you guys give me? I can tell his girlfriend really likes him and there's no sign of a breakup but I also don't want to leave him because he spoils me.