Need this off my chest

I love my boyfriend, I really do. I want marriage and kids with him but recently feeling for someone have been creeping up on me. I know it’s just a crush but I want it so bad. I could never hurt my boyfriend but damn I wish I could just say fuck it. We’ve had the poly and open relationship talk and he couldn’t do either of them. I don’t want that either. If I could I would just have one wild night to let my fantasy’s come true then go back to normal. I guess they’ll just have to stay in my head and hope when I stop seeing this person it goes away.....