Responses
This is exactly what people should do if they think they might be interested in someone else. If someone is seriously willing to have sex with someone other than their current partner, then they should be honest and break it off first. It's people who are selfish and want their cake and eat it too, who are easy cheaters.
Couldn't he just go to honami and like 'let's break up' and then go date terumi instead of cheating and risk getting caught? well, i like the manga anyway ╮(￣▽￣)╭