sgarecfinders | Specific kind of cheating fic (Reply)

As the subject says, I'm looking for a rather specific kind of cheating fic. I'm not even sure if there are any stories like this, but here goes.

Fics where one person cheats on the other, and when they confess their partner is unsurprised and has the attitude that it's expected that their partners sleep with other people (for whatever reason). Then the cheater feels like shit and vows to stay true to their partner or make it up to them or show them that they love them best or whatever. Happy endings a must!

One sort of example is in Straight as a Circle by

toomuchplor, when John confesses to sleeping with someone and Rodney isn't surprised, figuring it's just another one of his trysts to throw people off the truth (that McKay and Sheppard are in a relationship). It's not exactly what I'm looking for, but close.

My auto preference is McKay/Sheppard (in this instance, Sheppard being the cheater), but I'll take any pairing. Just please let me know what pairing it is that you're rec'ing. Thank you.