Awwwwww. Instead of pursuing in romance, all three characters stick it being friends in order to make everyone happy.
This is why I love friendship more then romance.
Btw, if one of the romances was fulfilled, don't you think it would be a bit adurpt? Think about it, their are many examples of love triangle manga's that are either stretched out to make more profit whilst killing the plot or a ending that has two characters start a relationship through plot-devices pulled from their own ass. This ending is sensible nor is it rushed, so it's decent. Yeah, the love is lacking, but all of them are happy. Ain't a happy ending enough?