Normal?

Anybody else married and straight but you think about doing sexual things with girls during certain times of your cycle.

I'm very straight I could never be in a relationship with a woman but sometimes I get this fantasy/thoughts about doing sexual things with women like it turns me on.(I love my husband very much and he pleases me so much to my liking)

I just want to know is this normal, am I the only one, is it just a fantasy and could I be bi?

I'm going to stay anonymous so I'll answer questions here as edits.