@crinrict: Thanks for responding. Yeah, I did delete the cache files. I also had removed all of the mods in an attempt to try it vanilla, but nothing changed. And as for the roommate situation, the Sims that were asked did agree, but never moved into the dorm- just continued to roam their old dorm. Tried resetting them again, but same situation.
I followed the Lessons tab on how to advertise for roommates (according to them, I should have found the option under phone > "Real Estate..." > Advertise for roommates), but saw nothing.
I'll see if just removing SP again will do anything.
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So update- I actually did nothing but reload into my save and everything (except the whole roommate issue) seems to be working now. How...odd. Occasional bug, maybe? I did have the Sim not going to class in the Brain Enhancing Machine to change their personality, so I have no idea if that contributed to anything. Regardless, the whole roommate system and advertising for them is still giving me troubles.
Oh, and it is possible to have two Sims share a double bed - you just need to set ownership on opposite sides of the bed. Hope that makes sense.