How do I tell my boyfriend that I have never had orgasm with him?

Description

I'm a 21-year-old girl and I have been dating my present boyfriend for about a year now. I recently met a cute guy who happens to be really nice and understanding.

The other day I went to see him and we had a make out session that made me have orgasm over and over, something that I've never experienced with my present boyfriend. I'm tempted to go all the way with this new guy, but I don't want to cheat on my boyfriend. How do I tell my boyfriend that I have never had orgasm with him? And that I would want to feel all that pleasure with just him because I love him so much?