Ishikawa Yuuto
In the words of every teenager Ishikawa ever had the displeasure of meeting, that right there was way too much information, about somebody he was doing his best not to care about. "A joue is not a dress! Although with the clothes you are wearing, I suppose it makes sense that you would not know the difference."
Ishikawa liked to think of himself as a calm person. Normally, he really was calm, despite biting comments implying the contrary. For some reason, though, being around this woman simply worked him up, making him revert back to childish acts of revenge.
"Does it look like I would be able to swim like this?" He waved an arm at her for emphasis. Though his clothes were not overly restrictive, the water still would have weighed him down. As a man who genuinely neither was strong nor capable of actually swimming, following her in would have been a terrible idea even if he were still alive. Those last parts, however, Ishikawa honestly did not want to tell her about. She would be insufferable about it, he already knew.
"Your husband was likely a piece of garbage anyways," he shouted back with a vague death wish. If it got her out of the river, though, even to strike him, it was still probably worth it. Although, he was wondering again why exactly he cared what happened to her. Maybe if she died, he would be stuck with her. That seemed like an adequate reason. "You could have surely done better than that."
Besides, Ishikawa did not think he was wrong in saying so. The woman, he discerned, had probably not wanted the divorce. She wore her wedding ring still, too, which indicated a degree of attachment. She was also relatively young, possibly married young or, if not, then the marriage had been short. Ishikawa came to the conclusion that her husband was firstly unreliable for breaking a lifetime commitment so early on and secondly, completely lacked the motivation to stand up and face his problems. He was, in other words, a cowardly quitter.