why do some people cheat on their partners?

this is a quick one as i haven't posted for a long time, i am being held up by lack of technical proficiency which is preventing me post something else i have ready [chorus of: we want the hot water bottle story, we want the hot water bottle story]

in the meantime i have some questions:

- what is it that makes a man cheat on his very warm, funny, gorgeous wife who has gone away for a week with the young children, left him to his own devices, even left cooked meals and left them in the freezer for him so he won't starve while she's away?

- what is it about this man, that makes him then call her every day that she is away? [perhaps so she doesn't call him first at the wrong time and then perhaps interrupt him sharing said nice meals with his whore? just before he sleeps with homewrecker in marriage bed]

- how can a person have an affair for a year with someone? that's not a "slip"

- how can that person look his wife in the eye? take her to his breast? tell her he loves her?

- how can that person look at his children? bear to think that his little daughter might grow up to also put up with having a fucking shit of a husband, or that his innocent son might grow up to be a cunt who cheats on his women?

- how can i as a woman know all this, look my lovely friend in the eye, laugh with her, drink champagne with her, listen to her talk about him, mentally flinching each time she mentions his name, knowing that i hold information that would blow her world apart?

i wish i didn't know. i wish the person who told me had not done so. i want it all just to go away. at least she will go away later this week and i don't have to feel i am betraying each time i look at her, be in the same room with her and don't grab her by the shoulders and shake her and tell her

YOUR HUSBAND IS A BASTARD; HE IS FUCKING ANOTHER WOMAN; SHE THINKS HE IS THE ONE AND HAS SAID THAT SHE WILL GET HIM IN THE END. SHE DOESN'T CARE HE IS MARRIED AND HAS TWO YOUNG CHILDREN.

how does he live with himself? how do i live with myself? i just pretend it's the right thing to do, or NOT do, to NOT tell her.

and she sleeps now in my guest room. i am sitting here up too late. feeling bad.

let me just push it away.

that's better.

[possibly identifying information deleted here]