My issue recently has been when I put my sims to sleep. They have a long pause, go to sleep, then immediatley they get up even though their needs are fully met. Im not sure why they keep bugging out ...
Ideas
I think you might be right, for me the cuddle option doesn't work at all they just wave cos they can't route to do the interaction. But for me the sleep option also disappears once one of the sims is in bed? and sometimes they will auto go to sleep with the partner and stay in bed. but other times I can only trigger them to nap through the needs bar but then again sometimes the needs bar triggers sleep for them?? it's so confusing.
While fixing this Sims just lie in bed after woohoo instead of sleeping/no sleep moodlet | EA Forums - 11949790 I noticed the bit you mentioned about routes failing when trying to cuddle in bed.
I'll look into this and the other issues mentioned in the OP when I get the chance.
One thing in the OP though, the cuddling while sleeping has been a feature for longer than Lovestruck unless I'm mistaken and at least from my experience, it USED TO* work flawlessly - I don't know about now because I haven't actually played that much since Lovestruck released. When one sim slept long enough they'd wake up and the other sim would readjust in bed and continue sleeping.