How do you think events would have turned out if the apothecary had refused to sell poison to Romeo?

Question

romeo and juliet

Answer 1

There are much worse things that happened than the apothecary giving romeo the poison.

Balthasar telling romeo that juliet died, for instance is more important.  As is the failure to get romeo's letter delivered.

Answer 2

Since Romeo thought by error that Juliet was indeed dead I don't think it would have changed much. He would have found some way to die to be with her

Answer 3

Nothing would have changed except that he would have used his "happy dagger" before Juliet did. Or would have found some other means of getting the poison.

If you're looking to lay blame on the Apothecary for the tragic end of Romeo and Juliet, I'd say examine closer the Nurse and the Friar.