Usually the first practice marriage is enough
I went 24.5 years in my first. One day I realised just how miserable and pissed-off I was every single @#$& day and for a change I snapped back and yelled at her. My first time ever getting that angry with her. I realised right then that it couldn't go on, there were numerous problems and dark thoughts were on my mind far too often.
We were adults about the separation agreements. We still own some things together and mostly get along. She is very hurt by it all, I was her first ever relationship, and that's what kept me there in the relationship for nearly 10 years, knowing how much it would hurt her. In the end, I should have walked out the door at least 5 years earlier but ...
... now I have a wife who I mostly get along with. Her only real complaint about me is that when I say no, I mean it. Her household was, in my opinion, far too empathetic (4 sisters might do that) and there are things which you simply don't do. For instance, don't buy our overweight, disabled (step)daughter a full-fat caramel latte when she asks you to. Say no, and mean it. I have no trouble with that, and have been known to tell her exactly why, which makes me a jerk sometimes, apparently. It's all paying dividends, though, because my wife sees that I simply don't get asked to do these things because the answer is already known. Confrontation has become unnecessary for me.
I guess the point is, communicate, even if it isn't what the other wants to hear.