A bride was left furious after discovering that her sister-in-law had eaten her wedding dinner while she popped to the bathroom.

The newlywed took to Mumsnet where she asked fellow parents whether she was being “unreasonable” to be annoyed over the situation.

Posting in the parenting forum the anonymous woman explained that she had no more than “two or three bites” of her dinner of stuffed lamb before she went to the restroom.

She and her bridesmaid went to the bathroom together and ended up chatting for several minutes before she returned to her seat.

BRIDE ALLEGEDLY TELLS BRIDESMAID SHE CAN'T BRING SON TO DESTINATION WEDDING

The newlywed took to Mumsnet where she asked fellow parents whether she was being “unreasonable” to be annoyed over the situation. (iStock)

She wrote, “Walked in, saw my [sister-in-law] sat in my seat next to my new husband, thought it was a bit cheeky but fair enough, I'd left him for a bit eating his meal.

"Approached the table, to find my SIL had FINISHED OFF MY PLATE???!!! I didn't know what to do except stand there a bit shell shocked! She apologized for been sat in my seat (didn't mention the food) and started to walk off, well my jaw must have been on the floor.

"I stopped her and asked her if she'd eaten my food and in her words 'yes, I figured you'd had enough as you're dieting and you walked off and left it'.

“I was speechless, she’s stood there with a smug look on her face, my husband's sat there looking sheepish, I explained to her I'd simply gone to the toilet and she said 'oh sorry, well there's still dessert I guess' and walked off!”

The incensed bride then questioned her hubby as to why he hadn’t got involved.

She continued, “Asked my husband why the hell he let her sit there and eat my food and he turns bright red and said he thought I'd finished too. Great. Fuming.

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"Didn't want to kick off on my wedding day and make a scene so sat back down in front of my empty plate, looking longingly around the room at the people eating slowly who hadn't yet finished and pretended everything was OK."

But while the bride’s in-laws certainly didn’t see the big deal fellow Mumsnet users were equally shocked, commenting to express their outrage over the guest’s “awful” behavior.

One said, “No you are not being unreasonable and I can’t believe she wasn’t embarrassed at all. That’s so awful.”

“I would be furious!! Who does that?” added another.

While a third commented, “1. Who the hell eats someone else's meal unless they have been told they can finish it?

“2. Who the hell does that at a wedding? This isn't finishing a plate of chips at Weatherspoon's!

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"3. Who the hell does that to the bride?!?"

The thread has since been deleted by Mumsnet.

This story originally appeared on The Sun. Read more content from The Sun here.