Bisexual problems

Do any other bisexual girls here have a struggle of wanting to have sex with a male or female when already in a relationship with one of two.

Ex. I’m with a girl but I’ve been wanting to have sex with a guy.

I sometimes desire the opposite of what I have.

so I want to have sex that involves penetration of a male.

I feel like she wouldn’t be cool with having a threesome either so this sucks 😂