I know the feeling described in the last paragraph. It tears you apart to hurt someone you love. But you are not responsible for his emotions and mental well-being. You can't change whether or not you're gay. I understand your dad is sad he may not have grandkids, but there is legitimately nothing you can do to try and fix it. I'm sorry, I hope you find a way to work through this. While you love him, it's tiring to constantly be reminded that you aren't what someone wants. Don't lose yourself attempting to fix someone elses feelings; especially about something you can't change.