Not sharing any hobbies or enjoyable activities together, like, at all:
Not doing things together for pleasure/recreation.
Sure, it’s normal to have some separate hobbies. Maybe one is into book clubs and the other is into gardening, and they do those things separately. But when you do absolutely NOTHING together except things which are obligations/work, the relationship is headed for the end.
My partner says that’s how he knew his marriage to his ex was doomed. She never wanted to do anything with him- even activities that she enjoyed or at least didn’t mind. She also never asked him to join her for any activities that weren’t family obligations.
Well, that and her fucking some other dude for two years behind his back…
Lack of communication:
Not talking about issues but letting them pile up inside.
Especially if you’re bottling them up because you’ve gotten negative reactions from your partner every time you have brought them up in the past. I know that I’ve stopped telling my mother about any of my problems because all she does is invalidate and one-up me. I learned that it just makes me feel even worse, so I keep it inside.