I'm not going to support my friend's new relationship
Why don't you want to support your friend's relationship?
I don't like his annoying girlfriend, she has a hideous voice
You don't have to like his girlfriend. You can keep this to yourself, it's not your relationship.
Meh, I'm telling my friend that I'm not going to support his idea of a relationship
It's important to be happy for your friend as long as he is happy in his relationship. Maybe you should take time to get to know your friend's girlfriend before you judge her.