It feels like a parallel universe right now, you know? - Oh, I do! You'd be astonished how many women know exactly what you mean.
In my support group, we call this 'stepping through the mirror'. You know, some people's minds create a definition of the world, which is similar to most other people's worlds but differs in very significant ways. Like Alice through the looking glass. By patient coaxing & persuasion, they bring their partners to their side of the mirror. The partners get used to it but, unlike the 'mirror people', they know it's not the only possible world. So there is always some discord. When, eventually, it gets too much for a partner and she chooses to venture a foot or a hand back to the 'normal' world, the mirror person feels desperately anxious: he's incapable of making this move; he knows she can leave.
Half in, half out of the mirror, you naturally feel you can't tell which side is real. It's a weird & scary feeling. Wait, this side is where you belong. Almost everyone else is over here. This is the world where humans have a broad, natural and flexible range of emotions. Where people treat one another considerately; where options are many, choices are free, and possibilities exciting. Where you may stand alone or shoulder-to-shoulder, and change your mind whenever you want.
Unsurprisingly, everyone in my group is very fond of films like The Matrix
They codify the experience of making this step!
he's climbed into bed and covered himself with the duvet
Have you seen the long-running Emotional Abuse threads on this board? You'll find them helpful, I think. They grew out of an earlier series on separating from partners with personality disorders. Before anyone has a go, about half of the partners in question had been diagnosed.
One thing we ALL noticed was a tendency to go to bed & pull the covers over their heads when the 'real' world threatens to intrude on their mirror-world.
Much of this will look bonkers to you. You're clever at researching - give yourself a little crash-course on Cluster B Personality Disorders. I believe you will find some explanations there.
It's not you :)