Nobody does ? But you can't blame him for falling in love with that guy. Married or not, there's no point in being glued to a relationship you're not happy with. It's shitty, but we can't choose who we love.
He could have maybe, idk, divorced his wife if he was SO unhappy before he slept with his student
You may not be able to choose who you love but you can choose not to be a shitty person who sleeps with your student knowing you have a wife and child waiting for you at home. Periodt.
I hate infidelity