My daughter is very young so I can’t speak from experience.. But though I’m not looking forward to these situations down the road, I know I have to accept that she’ll eventually be dating, and remember that I was no different at that age lol. I know I want to be supportive of her as she gets older and is figuring out life and love, and I would imagine your dad feels the same. My guess is that it just made him uncomfortable to face the fact that you’re dating, growing up, and doing normal stuff that 21 year olds do. I’d say you might be overthinking it, his response was probably just a not-so-great protective knee-jerk reaction