I have Alissa cock-blocking me, is that supposed to happen?
yes! you need to have her cock-block you in all three activities (excluding the dungeon) then go to sleep and talk to Cassie again
make her change clothes a couple times, when she refuses, "make her"
Also make sure she's not pregnant!
Yes! As mentioned, needs to happen three times. Most people miss 'annoying' Cassie!