Why do you think couples start to disrespect each other? Is it inevitable?

I'm respectful with people I don't know but naturally with people I am close to, I might do something that is considered lazily caring for them it's not that I don't or I ignore them completely but I can be a brat for lack of a better word. If I don't get my way with them I might cry because I'm upset and forget how they might feel in those moments, and of course anyone would feel like they're not in the right relationship with me but I don't know how you would avoid this. I don't want to agree on everything or have exactly the same interests cause that would be typical and feel like they just live to please me but I also don't want to not show I'm upset if I truly am and still let them know that I care and I'm just a human. Guys go on to date other girls but I don't really know what could be different. Other than like, she may not even have time to disrespect him because he is not a priority to her. I will make time, but expect my mood to be different if we're talking all the time for so many months, eventually I'll go through something and would like support or want to do something together and expect him to be there because it'll be nice for us to be a couple in public not just alone all the time. I don't know what do you think
Why do you think couples start to disrespect each other? Is it inevitable?
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