Help me choose, love or lust? I think. plz. gr8ly appreciated.?

I love my boyfriend beyond words can explain. But lately I feel our spark dying out. He does mean everything to me, I just feel we have gotten too comfortable with each other. Anyways, recently I met a new guy. It was completely random, and we hit it off. Nothing went down, I didn't cheat. I just want him. badly. his personality, it actually makes me laugh, he's spunky, outgoing, got a car, and respectable. the other night at like 12 am he took me out to a place that has the city view..it was absolutely amazing. the farthest we went was holding eachother and sharing a blanket. and we just talked for hours. He even pointed out, i can sense you're really comfortable with me. So I guess I am, he doesn't intimidate me; he brings out the fun in me. Although he is a little of a party-er (who isn't nowadays?) he respects that I don't smoke and drink and that I am a virgin. I can not get his laugh or smile or scent out of my head. it it just there. I understand I may've cheated emotionally, but I'm not to blame. I texted my boyfriend several times to hang out with me, but he has declined it everytime. I text him "baby" and "I <3 you" 's but he just rarely replies. I realized that he lacks spontaneity and character and I almost feel blocked with him. Help, if it helps, I am 18, the other guy is 20 and my boyfriend is 19. We have been together for three years... I am beginning to feel that our relationship ran its cours. that because I love him, I need to set him free, and if it was real love he will come back. I am just so confused. What would you do? Do you thing the other guy is just trying to get in my pants?