yeah I get it, if your plan for her is not sharing its not easy to add it that will not mess it up.
theres also the question of who.
I mean, u can add some nerdy friend from school that is in love with her and the MC can decide if put him in place or let him try. he could even give MC money, like he "helps" him get close to Kara.
like giving him pictures, both sexy but eventually nudes, give him panty etc.
but also dates with him (non-sexual) that u tell her to do. all for money.
eventually he wants more, and u could have blindfold/gloryhole etc. and when its impossible to hide it from her
he will be invited. and this can be all a side-route without affecting the story.