<human>: I've been with my boyfriend since my first year of college. He's the first guy I've been with and I'm the first girl he's been with. When we first started dating I honestly didn't think it would last, but it has. We have a great relationship, sexual and otherwise. Typical love story.

My problem is that I can't help but want to sleep with other men. I just want to know what it's like. Lately he's been bringing up marriage a lot and I don't know what to say. I want to be with him forever, I know that, I just want to experience what it's like to be with someone else sexually. For some reason, I can't get it out of my head. And no, he's not bad in bed, we have a great sex life. What is wrong with me? It's not fair to him at all. He's always there for me, caring for me, loving me, he even saved my life last year.

I brought up the idea of having a threesome and he said no, to guy or girl. He actually seemed disgusted at the idea. I know you're supposed to talk to your spouse about stuff like this, but I highly doubt he'd be happy to hear that I want to have sex with other guys. I think it would really hurt him if I told him. 

When I think of only being 60 years old and having only slept with one guy, I think I'd regret it. But at the same time, I can imagine a 60 year old me, single, really regretting throwing away a great relationship. I really don't know what to do. Is this something that will go away? I didn't have any of these thoughts until he started talking about marriage.

Can you summarize the given text in a few sentences?
<bot>: I [F23] I want to sleep with other men but I don't want to lose my boyfriend [M23]. How do I make these feelings go away?