I'm a tall (6'3") white skinny/toned guy... I get looks everywhere I go. And yet, guess what? I have never been able to score a girl that was attractive by most guys' standards. My ex-gfs would be considered average at best (not meaning to be an asshole).
I had huge feelings for a Chinese girl at work. And I have a feeling she felt the same way as I was constantly hearing about her talking about me. She would message me all the time, etc. Yet I asked her out three times and she shut me down each time. She was probably really suspicious too.
Anyhow I don't blame you. This is why you see average girls dating attractive guys and vice versa A LOT.
Most people assume negative things when someone attractive likes them. They may assume s/he's a fuckboy/slut. If I were you, I wouldn't let those suspicions get between you and him, you may be missing on a real keeper, you never know.
I would say the question should be directed to your own suspicion. Why do you think there is anything strange about his interest in you? Take a look around at the real world. How many gorgeous couples are there with respect to good looking women and good looking men? Hint: Not many. It is not at all unusual for one partner to appear much more brilliant than the other. Much less normal for both to be brilliant looking people.