Just because an additional guy would be enjoyable to her doesn't make her a slut. Just my viewpoint. Don't make it so dirty, allow her to see it in whatever manner turns her on. My girlfriend likes calling it her "fling"; a romantic getaway.
My girlfriend is pretty straight up Catholic. But when our sex life became a bit mundane for her, she took a lover.
She really enjoys it. I got over my insecurity and now it turns me on. She sees him every 2 months or so.
I think that its up to you. I have an above average cock. I have had hundreds of women. I have been told that I am a creative lover. Her taking a lover doesn't mean there is something lacking in me.
Adding spice to our sex life doesn't mean that I am inadequate, even if I feel that way sometimes.
We think its fun, she's happy, I have great and creative sex with her once again. We are both glad we experimented.
Just because a woman enjoys the attention, doesn't mean she will leave you. What other man is secure enough to love her, stay with her, and allow her to have whatever kind of exciting sex she wants?
You only live once. (both of you). Real honesty is real intimacy. Making allowances to insure that your partner is fulfilled can be an act of love. (It can also be an act of pure lust)
When she comes home and tells me that he fucked her four times in one night, I get hard as a rock. And she likes it when I get that hard and excited.
Now, all she has to do is start talking about it, and my dick gets as hard as it did when I was 20.
Now, when I jerk off, I fantasize about her on her back with her legs wide open. He's pounding away and she's coming like gangbusters. (when she comes, she starts biting and slapping.)
By the way, the bull has a small dick, but she enjoys the variety and says it hits her "button" just right.
Bottom line, we are having a lot of fun, and if you loosen up and go for it, you might find the same.
To reduce the angry and jealous feelings, embrace the cuckold attitude. It actually feels good, but you must cultivate it, while avoiding the "macho" attitude.
I have had no more exciting sexual experience than being "cuckolded"
Attached pic of my honey.
I will make you crazy.