I don’t think I can help with a why, but I can share my own bizarre stories of when I broke up with my narcissist ex in my mid 20’s.
We lived together and we had to continue living together until I could find my own place. One day, he would nicely offer to help me find a place, be calm and rational and kind. The next, he would be cold and silent and burst out in tears, calling me a whore because I had made plans to go out with friends that upcoming weekend.
Expect extremes. One minute being sweet and trying to get you to have sex, the next erupting in rage and calling you names and trying to make you feel bad about yourself.
Once I found a place, he and his dad kindly helped me move. I’m 5’1, 100 lbs and it saved me a lot of money on movers. I thought there was a chance we could stay friends.
A few weeks later, he held the few belongings I’d left at his place hostage in an attempt to get me to take him back. I had to contact his family to intervene on my behalf.
A few weeks after that, he attempted to STEAL my dog from our mutual friend’s house. They were dog sitting for me, and weren’t expecting him. He stopped by, saw my dog, and picked it up to leave. My friend called me in hysterics and I could hear her husband and my ex yelling in the background. I had to threaten him with police action and our friends had to threaten to stop being friends with him before he finally put the dog down and left.
A few weeks after that, I received an email with an attached certified letter, and the same letter to both my home and my PLACE OF WORK, that he intended to sue me for “our” dog. It was on attorney’s letterhead. He didn’t include any REASON why he should have any rights to a dog I bought on my own, with my own money, and for whom I paid all vet bills. But he intended to sue me. I ignored it and he never sued.
By that point, we hadn’t talked in months. He suddenly called me one day to chat in a friendly fashion to tell me he was moving to Costa Rica. He’s been there ever since.
There just really is no understanding the behavior of narcissists. They don’t live in the same world we live in. They don’t operate by the same rules. To them, other people don’t really exist. We are just extensions of them. So they don’t need to be consistent over time so that other people feel safe with them. To them, other people don’t exist, so who cares if they are able to cultivate friendships? Their behavior isn’t driven by the same things OURS is driven by – self-expression, and desire to fit in. They ONLY have the self-expression. They have zero desire to truly fit in and be like others. They are better than other people, so why should they either try to be like them, or strive to be liked and accepted by them?
So ALL of their actions are driven by self interest. Pure self interest. If you’re being “good” (ie, not actively talking about moving out, breaking up, etc) they will literally pretend that everything is normal and treat you “well” in an attempt to get you to conform to their will and “go back to normal.” I think THEY truly think this could work. “If I just don’t bring it up, and am nice to her, she will forget about this whole ‘breaking up thing.'”
But if you’re being BAD (asserting your intentions to leave), they basically throw temper tantrums, because they’re used to getting their way with you. They’re used to at least THINKING that have control over you, and all they want in life is to get that control back. So they just switch from tactic to tactic to tactic to try and see if any of them will get you back under their thumb.
It seems manic and crazy from a normal person’s POV, but to them, they’re, like, trying different ways to train a dog. Like, oh, positive reinforcement didn’t work, let’s try hitting it on the nose with a rolled up newspaper. Oh, that didn’t work, let’s try the positive reinforcement again. Oh, that STILL didn’t work? Annoying. Let’s try kicking it.