Territorial sibling cats
I have 2, 6-year-old cats, Ruben and Richard. They are both male and are from the same litter. They were outdoor cats during the day and indoor cats at night, as we lived on 700 acres with no neighbor, so they have always used and liked the litter box and had no problem using it when they were in the house.
Ruben has always been the dominant cat. He is more "loveable" (although they are both the most loveable cats ever), and Ruben always wants to be with everyone in our home. However, 2 years ago we moved from the farm to a neighborhood setting, which they didn't take very well at first (spraying and being a little hostile). But with time and encouragement, they have settled in.
In this new house, we have 2 floors. Ruben has claimed the upstairs and Richard has the downstairs. We keep the food upstairs and the litter boxes downstairs to try and combat any territory issues and they don't have issues (other than Ruben always eats first) eating or using their litter box. Both cats do like each other and share their spaces throughout the day.
Recently, Ruben has been getting increasingly attached to me which I welcomed at first because he’s great and I love him, but he has taken to marking in my room, presumably because he doesn't want Richard going in there.
He has peed on my bed twice now and always wants to be in my room. I resorted to keeping my door closed at all times, but Ruben has started to show some distress from not being allowed in.
How can I combat this territorial issue? I love having him in my room as he sleeps with me but the marking just cannot happen.