It would be really nice if you got to keep the filled condoms from working at the brothel as items. You could drink them at any time to replenish a little bit of hunger (and heal if you have the perk for it). You could also use them in battle to arouse both you and your opponent by drinking them, pouring them on yourself, or emptying them into your ass, possibly even being able to bulge out your stomach on demand. Whatever you could do with them, I definitely want to keep them.
It could maybe even be a general thing that you could use condoms in order to save cum for later. I'm not sure it could ever make sense to be able to slip one on your opponent and prevent them from taking it off long enough to have them fill it, but you could certainly wear them yourself, and then your cum wouldn't have to be shot "uselessly" into the dirt all the time. I guess there would also be the downside of not burdening your opponent with your semen when you cum in them too. On using it on your opponents, you could make them use one whenever you're in control: when you jerk them off, blow them, or sit on their dick. Making them wear a condom before you ride them would give you the bonus of not being filled up, though I guess you would have to use a turn to peel their condom off if you wanted to keep it.
If they're in control, maybe if you've seduced them enough they won't bother taking the time to take it off before fucking you.
I didn't have all this in mind at first, but now I'm thinking condoms could be a legit game mechanic. I feel like a "Condom Collector" perk would be appropriate. I'm imagining an NPC that sells condoms, both empty and full, with her scant clothing having tied-off semen balloons in place of fabric