I couldn't care less about the cheating tbh. Surprisingly, I think Akira puts her in her place regarding that from the start, and he never takes a step back on that regard.
As for Haruka herself, her husband is gone for three years, there's no way of knowing if he's even alive, she took a chance on a new relationship and found out she liked it better - good for her. The issue is that she didn't go "I want to break up with my husband, it's just that I can't get a message to him." If she had the intent to break up with him I think a lot of people would be fine with it.
Obviously, the correct thing to do would be to break up with her husband before dating another dude, but again, war. Life is messy. The real issue with Haruka is that she's a predator imo. She hires teenage girls because she wants to have sex with them.
They will. You'll see such beautiful things. But lasting happiness? We're not there yet.