What should Buffy do?
Perhaps, think things through, know if her heart is in the right place in terms of anger, giving a chance, denial, what does she really want, etc
Remember, there are things, places, people or events that act as the path – they could direct her to where she should be.
It does not and never always meant that she stays there.
Maybe Buffy met Yno to bring back Alex to her.
(TheCuriousMe: or the other way around?)
They don’t always tell you that they are the right one.
Remember, you meet several guys before you meet the right person.
Buffy should be wise enough to discern to follow her heart and her mind.
Both guys should prove their sincerity by talking to Buffy directly. Moreover, the guy who deserves Buffy is someone who’s willing to be with her (wherever she is) and help fulfill her mission.