Scramptha has some good advice: Don’t tempt the universe.
Getting a tattoo of your so’ s name is always a dead give away in my experience. The universe doesn’t let ironic potential like that go unrealized…
Letting resentment build up and neglecting to communicate on top of that:
If you build up resentment for your SO, you are constantly thinking the worst about the other person and one day you will see that your only way to happiness is to drop the relationship. The trick is to confront issues head on, talk a lot, do whatever you can to not build resentment. It is t always easy, and both partners need to be willing to work stuff out.
There was a social scientist who said he had a 90%+ success rate of knowing whether a married couple would divorce or not based on 30sec of conversation between them. Even if they were laughing or joking, he could tell if a joke came from resentment and would conclude they would eventually split.
Which really is just another way of behaving in ways that John Gottman would call the four horsemen of the apocalypse: criticism, contempt, stonewalling, and defensiveness.
Because sometimes, arguing is important and necessary:
This is the biggest IMHO. Fighting is important, and a willingness to see issues through to a resolution shows a willingness to do anything it takes to make it work. Nobody wants to fight, but of you don’t the issues fester. I always say “if you keep sweeping everything under the carpet, eventually your floor is too lumpy to walk on.”