I get alarm bells when someone just wants to make someone happy for no reason.
Made sense when he wanted to make her happy since he sympathized with her situation and also wanted to make her try things she's never had before - but wanting to make her the "happiest in the world" is like... Why? You barely know her. You haven't even fallen for her yet lol.
If I had to guess, it's some kind of Japanese cool/tough guy thing that men shouldn't like sweet things. There's no evolutionary basis for it. Of course limiting sugar intake is excellent for the general health, so as such it's not bad.