Oh sorry I didn't realise you meant love was way behind. Basically you just have to sleep once her love is maxed and it will level up. You probably have to do it a couple times to catch all the way up. You can ask Christine to help with Lydia in exchange for reward points, that should give you a big boost to the grind. Fair warning though, you probably won't unlock much besides the final love story event for the effort.
The Krissy love/lewd is something I'll revisit if and when she's actually available outside of the party. Just something that got pushed aside because of time constraints.
Jen and the club, I'm pretty sure there is a conversation you have with her at some point, probably one of the dinner ones where she becomes aware. You probably just missed it, as they are randomly selected. For simplicity's sake I sometimes have to assume minor things like this actually happened in the previous content stage. Otherwise tracking and accounting for it all in the dialog becomes a bit too much.
Lydia definitely doesn't magically know about your ways. For much of the story with her, you aren't in a relationship. You have the party girls, Krissy, interactions at work etc. She'd have to be the most naive and clueless person alive in order to not have some inkling that you're messing around, and she has no good cause to stop you until later on. At that point, well she has her reasons for not doing so. There's hints in the dialog, with her and Krissy. I know there's a lot of it, but it's all there
Anal stuff will be locked behind anal skill. Only thing I can imagine to be added is maybe selling her ass in the prostitute content. Locking her story behind it was a mistake I made, and I'll take it into account going forward. So aside from that part, I wouldn't worry about being forced into it.