Has your wife ever wondered or asked you why you find it so exciting to share her?
It's actually hard to describe. Harder for someone to understand if they are not in the lifestyle.
For me it's witnessing my wife willingly "entertain" another man's cock. It's kinkier when the other male is a stranger we met online or on vacation.
Seeing her let some random guy put his dick in her. There's some sexual foreplay, she usually blows him, he'll suck her tits and lick her snatch. eventually it leads to her spreading her legs and letting him penetrate her. And she knows this is going to lead to him cumming in her pussy. She's letting a complete stranger have her most private body part to be used for pleasure. It's her behavior, whether she's acting it out or really feeling the horniness of the moment. A male she doesn't know, has his hard dick in her, she allowed it, and she going to let him fuck until he releases his load in her.
I'll watch, and when he withdrawals, it'll be my turn to reclaim her. And still, she'll be aware that the sperm of one man is already in her womb and that now her husband, so sexually aroused will be filling her pussy with his specific sperm.