beta
I know that these situations are tough on Minato, but Shizuma isn't to blame! The solution IS NOT TO TURN A BLIND EYE TO THE BEHAVIOR AND HAVE SHIZUMA CHANGE HIS VERY WAY OF BEING!
The problem stems from Minato's trauma, and indulging the one stuck in a trauma in order to hide it away will never be the correct solution! They need to work together, talk it out, slowly but surely find ways that can soothe Minato's boiling fear of Shizuma leaving him, trust issues or whatever the actual reason for his uncertainty is. Of course it'll be difficult and slow to change, twisted mental beliefs are often like that and that's normal!
Because it is evident that Shizuma has and will dedicate all of himself to Minato, it's just that he is generally kind towards everyone. Hell, I'm like that too! And if my partner told me to be more rude/indifferent towards others, I just couldn't do it because it feels wrong. I don't flirt with others, I'm simply being nice. If that is enough for my partner to feel insecure, even I would feel hurt due to their lack of trust in me. It would feel like they're belittling my feelings and love for them, even if it's obvious that they just have problems that they need to start solving somehow.
I understand it can feel rough reading this from Minato's perspective and we want to emphatice with his pain, but Shizuma does not deserve the disparagement he gets from some of you.