Why Would A Man Want His Girlfriend To Sleep With Another Man?

Why would a man want his girlfriend to sleep with another man?

Because I want her to experience as much variety as possible, gaining beautiful new experiences. And because I want my girlfriend to have pleasure and the strongest orgasms she can have. 

Because I want to offer everything to the love of my life. I don't want our relationship to be the end of her fantasies!

Because I enjoy seeing her as the free independent spirit she really is. I know she is adventurous and she is allowed to be.

Taboos are hot. Breaking taboos is even hotter. Girlfriends are not "supposed" to have sex with men who aren't their boyfriends. Boyfriends are not "supposed" to enjoy watching their girlfriends have sex with other men. F*ck the social norms! My girlfriend can be her true self with me and live her fantasies!

Because it brings out her naughty side that I like so much.

Because I like to know that other men find my wife attractive. I think she is incredibly sexy and I want her to know that other men find her hot too.

I want to see how she reacts to other men's touches and thrusts and I want to see the look of complete devotion in her eyes when she obediently serves another man.

Because it turns me on to be in a sexual competition for my girlfriend (also called sperm competition). 

Because I don't think she is my property, even if we are in a relationship. 

For reasons of power: I find it arousing when I share her with other men.