Is my father being unreasonable?

Sounds like he's been unreasonable for a long time. The fact is, you're an adult now. You should never apologize for living your life, especially if that life is happy, healthy, and productive. Your father sounds like he's miserable, and wants to bring everyone else in his life down to his level. Don't let him do that! If he wants to act like a child, that's his problem. You're allowed to be happy! Be happy! You're engaged, you're college educated, you've gotten a job in a terrible economy! You're doing really well for yourself. Don't let one asshole ruin it for you.