Why are a lot of people very uncomfortable about interracial relationships?

I mean why? My late dad wasn’t a fan of interracial dating and prefers his own race but supports it. When I dated my first boyfriend who is Hispanic, I’ve gotten looks, especially disgusted looks and some of my family criticized me for it and said race matters to them and they prefer their own race. I’m a young white woman.
When I dated my current ex boyfriend who is white, I didn’t get any reactions.
Why did I get look and criticism when I dated my Hispanic ex boyfriend but not my second ex who was white?