I'm not familiar with the caste system yet, as I've not read too far into it. But you can slow things down and limit their interactions by caste. I still haven't read anything about pausing progression for inactive households. The Relationship module will let you change that number to a max that is somewhere around 20 in-game days.
The default is set to something similar to EA's story progression, at 3 days. While I was reading into this last night (the mods I linked in that post), I read that if you have the relationship module for Story Progression from the Nraas site, it sets all relationships to a certain number for the amount of time that it takes a sim go progress a relationship.