but countless times I feel like my dating sims are good at first, until I trash out my idea and the cycle starts all over again.
It's probably not trash. It probably just needs refinement.
I'm not much of a writer, so I don't have any advice on how to get better at writing, other than practice. If you are anything like me, though, you need to not just write, but rewrite.
My first attempt at a scene or conversation usually isn't great. That's OK, though. I just do the best I can in the moment, which I may or may not be happy with. Then I move on to something else. When I come back to that section later and reread it, I might think it's awful and despair that I wrote something so bad, but I will see ways to improve it, so I rewrite it. It's probably still not good enough, though, so I come back to it again later. Then I rewrite it again. I keep doing that until I have something satisfactory.
I am not talking about proofreading (although that is mandatory) but revising the text for better flow, better word choice, more natural dialogue, more evocative descriptions and so on. It takes a few tries to get it right. So basically, don't be discouraged if your work seems poor at a second or third look. Just keep going over it again and again until it's polished.