Oh dear, OP. That sounds totally awful. He is using the bathroom as his getaway or something, and that is kind of gross. I don't think it's that abnormal for one spouse to avoid the other by hiding out in an office, basement, etc., but even that is not good for a family relationship and is not nearly as odd as using the bathroom. Have you talked to him about it? Honestly, even if he was checking his phone while sitting in the living room, that would be better than locked away in the bathroom.
And, TMI alert, I get the need for bathroom time. I am a DW who has, shall we say, a slow system despite tons of water/exercise. So, I probably spend a 20 minute session each day sitting on the toilet and even that is uncomfortable! Toilet seats just aren't designed to sit on forever. Maybe I have hit upon a totally passive-aggressive solution - find an incredibly uncomfortable toilet seat or "break" that toilet so there is only one working in the house
