UPDATE: Micropenis husband now demanding $50k for penis enlargement surgery

A US woman says her husband has been left "crushed" and threatening to sue, after she turned to an online forum for advice about his micropenis.

Two weeks ago the anonymous woman posted about the "unexpected discovery" in the Reddit 'Am I an A**hole', under the username 'throwaway_peen34'.

'Throaway' explained she and her now-husband only dated for six months, before getting married another six months after their engagement. The pair didn't have sex until marriage; not because of religious reasons, but instead her husband saying he's "old fashioned like that".

"We got close to fooling around a couple times but it never went far. I tried, but he always stopped," she wrote.

It wasn't until their honeymoon she discovered her husband had a micropenis - around "an inch and a quarter".

"Am I the a**hole for reading into this and being upset that I waited until my wedding night to find out that he probably isn't as "old fashioned" as he says he is?" she asked.

"I honestly I don't even know how I'll broach the topic, I kind of feel lied to. Like a halftruth...or something was intentionally withheld from me."

Her post received thousands of mostly supportive responses, and received coverage across several major news outlets.

Its popularity came at a cost however; in a new post the woman writes that her husband became aware that she'd written about him, and was threatening to leave and sue her.

"He says he wants an annulment and is considering suing me for defamation of character."

While the original post was anonymous, the woman explained her husband saw it through an old friend of his "who knew he had a micropenis and saw on his FB that he had just gotten married".

"I feel like I am the asshole. He is crushed that I posted about him."

Other Reddit users were quick to jump to the woman's defence, telling her she did nothing wrong.

"He admitted that she might not want to marry him if she knew, but that was 100 percent her decision to make if it was important to her. And he lied about not wanting to have sex before marriage that's a huge red flag," one commenter pointed out.

"He tried to trap you into marriage without telling you something that is honestly very important. There's no limit to what else he will hide from you to manipulate you," wrote another.

While the woman's situation is troubling, it's also rare.

Healthline reports the average micropenis occurs in less than 0.6 percent of the US population.

They say an adult micropenis is a stretched penile length of 9.32 cm (3.67 in.) or less.

Newshub.