Is it o.k. to have a "crush" on someone while in a relationship?
That someone can't be everything all at once. Or can they. But that still doesn't mean unexpected challenges could come your way. It's all in how you handle it, or not. Being accountable for your actions and also being honest with yourself will either make it ok or not depending on that other person's feelings towards the situation.
I think it is normal human animal behavior to get crushes on others while in a relationship. I would tell my partner which would do several things. One, it would allow your partner to bust your chops and get some laughs out of it. Two, it would deflate the secrecy excitement. Three, you need to get real and be honest. And four, realize that the choices before you must be made. As they say, man up and let go.
Thank you for your comment. Seems reasonable.
You can't do a thing about it, acting on that crush is another thing.