You think he could fall in love with a robot over a weekend VR trip but can't fall out of love with that same robot over 30 years when he sees her repeating the same shit over and over? Come on man. He doesn't hate Dolores, he feels nothing toward her. He has accepted what she is.
I get that he would have a resentment over the situation after coming back to the park repeatedly and Dolores not remembering him. However, when he takes on the MIB persona, and kills Maeve, and the maze is revealed to him, and he says "for an instant, she was alive" I'm assuming at that point William would have realized that there would be a way to save Dolores and have her remember him (which she obviously did at the end when she said William would always come save her). That was my whole point. I think it would have been a better ending to the show to have the MIB sacrifice himself to help reveal the maze to Dolores so she could become self aware and escape the park. I like that ending more than having Dolores be Wyatt and kill everyone. It would've tied everything together really well with who he was when he first met Dolores.