Thoughts occasioned upon hearing the song “Rude”...
...or “You keep using that word; I don’t think it means what you think it means.”
There is nothing rude about giving an honest opinion when asked for one. It is rude, however, to dismiss someone’s opinion after asking for it just because it wasn’t the opinion you thought they should have.
If you were going to “marry her anyway”, then you shouldn’t have asked.
I’m not going to say that you have to have her father’s blessing to marry her, but since you asked for it, I have to assume that it is important to you. So perhaps you should consider striving to understand his objections and commit yourself to winning his approval. Rather than simply ensuring that he will never respect you.