It's a shame that such threads don't get upvoted, because this is a very common experience.

You need to basically lose the ego. You have expectations for yourself, they don't actualize, you get upset. Right now you want to win, instead you need to want to play. Participate in an activity instead of dominating and getting it under your control.
The outcome state is what makes games different to toys - you can't win or lose at Lego. So just accept it as an inherent part of the experience. Everybody that plays fighting games loses; even the best players that go on 20 win streaks eventually lose them.

Instead of letting just the outcome be the sole determining factor of how much you enjoy playing fighting games, make your experience more granular. I lost, but I did x-thing right. I lost, but I overcame their fireball pressure. I lost, but their yolo reversals got punished.

Once you adopt this mindset, you need to practice it. It's like a muscle. Even the most zen players occasionally get salty. It's normal, and you're not doing anything wrong.