Not surprised that he's gay, surprised that he's come out.
I'm actually really pleased. If more male role models are open about their sexuality, perhaps they'll help to normalise same sex relationships, especially amongst young people, which will inevitably reduce homophobia.
He can have every girl on this planet, yet he's dating a guy.
That would be because bisexual people are like... attracted to both genders? And perhaps he wants to have a real, meaningful relationship instead of grabbing and hot girl he can get? I mean, it's not that hard a concept to grasp that he honestly likes both genders and just happens to be dating a guy.
I honestly think he wasn't sure he liked guys as well as girls. Then he met a guy and it clicked.
I don't really think he's been in the closet or anything. I was the same.