I've never used Mods for this game, and I've definitely gotten the Cathy scene after banging Josy or Maya.
And it's pretty stupid imo that would be locked out anyways, storywise. The MC can literally bang several different women in the same Mansion while being in a relationship with M&J and having Neutral to CHICK alignment.
So why would he just be like, "No Cathy, now that I'm in a ship with these 2 girls, I will still have no strings attached sex with several other women, but I will not have no strings attached sex with you."
Very ridiculous, even more ridiculous if we're suggesting he can't get hard after having so much sex," Which irl, would probably be true. " But in this game the MC is good to go whenever.
But like I've said, I've never used a mod for this game, and still got the Cathy scene while in the relationship. Very strange.