If it's not too difficult to implement for you, my suggestion would be like this:
Have a threshold of some sort for events to trigger. Example: there is already an existing sex scene with Nikki and Johnny if you continuously have a drink with him, so it can be that after let's say the second time that this threesome happens Laura will catch you and the sharing thread will trigger and you can choose to have this happen or not. IMO, this also prevents some sort of disconnect with the story about Johnny knowing you have sex with his wife and wants you to share your wife with him too when you already had a threesome with them before. This drinking event with Johnny can also provide the trigger event for cheating since the relationship points with Laura decreases, so let's say again after 10 times that you had a drink with Johnny and the morning after your wife asks for sex and you don't give it to her then the cheating path can start. Of course, it can still be prevented if you don't want it to happen since you can have sex with her when she asks you for it. All of the threads or paths can have something of this sort and can also provide some repeatable events instead of having dead-end paths. Say, if you continuously visit Nikki and have sex with her, Laura will be suspicious and have a chat with Johnny about it and they will catch you and the stripper and/or pornstar thread/path can trigger. Going by this, you can trigger most of the paths in-game without having to manually activate it in the thread menu. Visiting Lily in the college continuously for example, can trigger Foxy's curiosity and also catch you and the Foxy with other guys can trigger or you can stop it from happening by not visiting Lily anymore.
Hope this makes sense for you and thanks for reading such a long comment