I like this manga and the mangaka. The mangaka didn't choose to push it and chose the reality because let's be honest this is what will mostly happen in real life (you're weird if you want them to actually be together). And it's also an open ending for the main story because even if most probably the guy won't fall in love with Wakaba, the mangaka left the ending to the reader. The forever promise between them can be interpreted by the reader as family love or romantic love so I really like it. But I'd like to think that they became a really close family. And I'm also thankful for the mangaka that the girl didn't turn bratty when they were turned down.
Futari no Table