If you truly love a flower you will enjoy its beauty but won't pluck it
This is whats happening, Koga going on that concert date might be nice for her, but creating the possibility of Aya and her friend making amends is good for Aya. And Koga loves Aya so she chooses the option that will make her happy.
On top of that there is also the Semi guilt her socially awkward ass is feeling.
And please stop complaining about chapters that aren't all fluffy wuffy, this isn't meant to be all fluffy wuffy