Women will also do this ethically as well. For instance I fell for this sales woman / instructor hard before talking about the sale. Right before her pitch it was,
Her: "Oh yeah, I have a boyfriend."
Me: "I was wondering when you were going to say that."
*More chatting about her boyfriend, He does martial arts!*
Me: "I don't study martial arts anymore."
Her: "Why not?"
Me: "Because I think I know enough and I know I am not going to get into a fight."
*training to join the Marines (never joined) I came to the conclusion that they didn't fight, they ambushed, skirmished, held position or tactically retreated all of which people confuse with fighting. UFC fighters fight, two evenly matched opponents go at it their skill separating them on the mat. Plus, I've decided to be a peaceful guy from now on. So it was technically true when I said I don't fight

but that's a philosophical discussion you'll have to PM me about.*
My point is I was straight up with her and set myself apart from her boyfriend. She has never once mentioned him again. He either doesn't exist, unlikely, or it's just not relevant. Women actually have to go out of their way to insert the "I have a boyfriend" move and have a good reason.