let's see if I can be more through. HYPOTHETICAL SITUATION:I disagree about him lacking commitment - he likes the childhood friend, and is actively trying to get closer to her. He deliberately tried to tank dog girl's feelings for him for that very reason. I'd say that's pretty committed.
Also, why should he get with Sayuki just because he knows she likes him? Has there been any indication that the feeling is mutual? I don't understand the mentality some people have where you have to get with somebody just because you can - if you know you don't feel the same way they do, then it's just disrespectful in my opinion.
Not knowing what WE know, that CF likes him, he should try and make things clear, in the case that she didn't like him that way, then a person shouldn't just stand still and wait forever for that person to change her mind.
He could get with Sayuki because, he doesn't love her, but he wouldn't spend so much time with her if he didn't like her as a person, is not like them getting together means they have to marry, they can go out on dates and if things don't work out, just leave her, at least is settled and she doesn't just hang on her dreams of what the relationship could be like.