I think Shizuma is a little self-centered, he doesn't recognize his own mistakes.. or mayb...

And his apologies are quite shallow.

Sorry if this turns into a rant but I hate shizumas attitude so feel free to skip if you want!

If you remember, he said that he wished his ex gf told him before she left him that she was having a hard time but SHE DID! She literally went up to him and got mad at him for not texting her back and not making time for her. He knows it’s not okay. He knew it because no one would be okay with it and more importantly, she already expressed she was annoyed. He ignored it because it makes him feel better because if he did think about his actions and what he did to his ex, he would feel so incredibly guilty that he’d be paralysed from the realisation of what he did to another human being and the fact that he’s doing the exact same thing to Minato. Minato is a brat and needs therapy but he’s been open and honest since day one and said he’s hard to love because he’s jealous and insecure. Shizuma knows this but does NOTHING to make him feel more secure. I’m talking text 3-5 times a day whenever you nip off to the toilet or to grab food or you have a quiet moment or in the passenger seat of a car going to your destination. I’m talking setting healthy boundaries with others. Literally anyone can cheat because it’s about temptation and no one is immune to temptation. Not even the best monk. That’s why they practice abstinence where they STAY AWAY FROM TEMPTATION! They literally have to distance themselves because it’s so easy to stray from the path you’ve chosen. If he wants to show Minato that he won’t cheat or leave, he needs to keep a good distance from other people and realise that smiles and being kind when it’s not necessary and laughing with a coworker when you’re meant to be going on a date IS the way you lose your partner. Those are all “red flags” and most people now don’t wait until you cheat. They leave you STRAIGHT AWAY.