The second sentence does not mean what the writer thinks it means… Change They all have bad memories to They all have bad associations or You have bad memories of them. (If you leave it as it is, you’re saying the dogs are the ones who remember bad things.)
Add a comma before and (compound sentence.)
Add a comma after loves dogs (compound sentence).
The last two sentences are potentially confusing because of the different uses of it. I recommend changing these somewhat and merging the sentences into one for the sake of clarity.
You hate dogs. You have bad memories of them from your childhood, and you have tried your best to stay away from them. Your crush loves dogs, however, so you now try your best to get along with your least favorite animal. Their dog refuses to make it easy, almost as if it is trying to get on your nerves.