Why to do??

I am in a long term committed relationship. I love my partner very much, he's my best friend and I really do care for him an immense amount. But. I have now caught feelings for someone else. These caught feelings are nothing compared to what I have for my partner but they are bugging me that they still exist. I guess what I'm asking is, is a little crush on someone okay if you're in a relationship? I would never let it escalate to more than that but I still want to know if I deserve to feel as shitty as I have been lately.

Pfa