Encouraging my wife to wear skimpy bikinis

I am 29, married, and I have a cuckold fantasy fetish. I get off a lot to imagining my wife getting fucked by other guys.

My wife is 27, and would be described as busty petite. She is 5’2 red head, with 32 D tits and around 115 pounds and a very pretty face. She is pretty conservative and usually dresses as so. Whenever she does dress a little bit looser, girls always comment on her body and how they didn’t know she was hiding it.

Whenever we go to the beach or swimming, I always try and convince her to wear a bikini over a one piece and have had some luck but she still tries to wear the most covered up suit she has. Any advice on encouraging her to wear bikinis more?

Fyi, she does not know about my fantasies as I think it would make her mad