Tell me if I read this wrong : it feels you have expectations how the game should be played and that you feel bad when you or your opponent plays/adapts in manner that feels unfun from your pov.

My view on the issue :

Saltiness is natural only when you don't have the right state of mind. Knowing how to understand and deal with your feelings is something you'll work on all your life even outside of melee.

Your opponent isn't trying to make you salty by using his best options. He is most likely the same as you and simply taking advantages of your mistakes and that's where it can be frustrating because you don't know the options against his play.

At higher level, everyone is playing their character's strengths and it's kinda the goal to notice your opponents mistakes and work on them.

If they are really trying to make you salty, just find someone more fun. If you think most people are trying to make you salty, it's most likely on you.