Advice Illustrated: Do you really want to do this?

Hope your Yuletide was merry, and that the New Year's celebrations will be fun and safe for y'all.

Now on to Pruditry.

Winner of the women's division of the How to Do Everything beard sprint

Letter 1 is from a woman who is boycotting intimacy with her husband because he refuses to shave his beard. I would say that she made a big mistake in demanding that he shave. Surely her feminine wiles would have been much more effective? And let's turn this around: what if he starts demanding that she shave her public hair? Does she have to oblige?
Prudie says to try another tack, and at least get him to groom his beard properly.

Video letter is from... Wait! There's no video letter, just a best-of the year's videos. Boo.

This painting was popular among the results for a search for "illegitimate daughter"

Letter 2 is from a child who hates her mother for having an affair with a married man (who was her absent biodad). Now she herself is having an affair with a married man, and hates herself but can't stop.
I say: he's the married one, not you. But if you don't like yourself for doing this, stop it. Was that so hard? If you're too weak to see him, change jobs, change cities. But I think you're just having too much fun flagellating yourself. And maybe vicariously punishing your mother or something.
Prudie mostly agrees, but of course adds in the obligatory "get counseling".

Letter 3 is from a person who is in competition for a job with a former colleague who was fired for embezzlement. It's not on her record, so should LW tattle? Or rather, how should they tattle?
Really, if they're not your employer, you don't really care, so your fake concern about her potential for ripping off her new employer is most implausible. I say it's your call. Tattle or don't. If you do tell, I'd bet they don't choose either of you.
Prudie agrees, and suggest working on her own interview skills rather than trying to take down her competition.

Letter 4 is from a guy who's got financial difficulties, and who received a generous gift of cash from family friends. The givers' daughter says that her parents know he's in trouble, and think of him as family and want to help. LW's parents think the gift is too generous and should be treated as a loan.
I have been helped at times, and have helped others at times. I see being the beneficiary of others' generosity as a source of no shame, and being the benefactor no great honor. It's the way society should work: accept help when offered and needed, give help when you can and see the need. "Pay it forward" is probably a better policy here than "pay it back".