Yeah i understand. My gay friend also same. But when he cheated on his partner, i wish they broke up. Because I know his partner loved him so much and he was very sweet guy. I even know with whom my friend cheated with, he is a player so he slept with many guys and girls. And his partner didn't know. Btw they broke up naturally. Never told the partner that my friend cheated him a lot. I didn't want to break his heart more. But I felt glad. My friend wasn't the one for him. But your story is very common in gay relationship, usually them with long relationship. They can't just switch partner especially if they are no longer young.
Even if you do something good for it, when it's the time it'll bite you and poison will run through your veins. Haruna knew what kind of man Ryu is, always. So, seeing this from other perspective, why he got mad? The chances of cheating was pretty high, considering they got together because one got curious and the other was feeling lonely
Maybe Ryu will understand what a commitment is, in time, at least he's feeling the need of being with Haru only and that's a nice feeling.
I have a friend who's gay. He and his life companion have been together for over 12 years and they had a crisis, because even if my friend was no saint ( and the same with his boyfriend) shit hit the fan when his boyfriend was feeling something more than lust with his lover. My friend cheated on him on purpose that time, his boyfriend got mad, they broke up. After a rough few months both of them felt miserable ( my friend even went to a psychologist because he was pretty depressed) and they decided to talk and being honest with each other. They concluded that it's more important to them the fact of being together as a couple, that they can forgive one night stands, but what is unforgivable is if they start to get serious feelings for another man. It's like "if something like that happen to us, what's the point of being together?"
I can't do that but I congratulated him because they're on another level for me.
That's not option for Haru either but it's a story, Ryu will change and theyt Will be happy ever after in their house ლ(´ڡ`ლ)