A bride has just learned her mother-in-law is gatecrashing her honeymoon.

OK, so everyone knows someone with a story about the mother-in-law from hell, but this one quite possibly takes the (wedding) cake.

After months of meticulous planning and research, a UK bride-to-be is furious after learning her mother-in-law has booked a holiday that aligns perfectly with her romantic honeymoon getaway. Same location, same resort, same dates.

But according to the mother-in-law, it’s all just one big, happy coincidence.

As she explained on Mumsnet last week, the bride-to-be and her fiancee had been discussing the honeymoon for months, sharing their proposed location and dates of the St Lucia getaway with their parents.

“Fast forward to last night and she’s posted on Facebook that she’s booked a holiday to the same chuffing resort she knew we were looking at," the bride-to-be wrote.

“Worse than that, the dates overlap so she’d be there for the first few days of our honeymoon.

“She’s making out like it was a pure accident but I really don’t feel that it is," the bride-to-be wrote. "She’s suggesting meeting up for a family meal when we arrive."

Listen: Ask Bossy advises a woman on how to ask her MIL to, uh, move out. (Post continues after audio.)

The woman says her partner is "also furious" about the coincidence but for her part, the mother-in-law is playing innocent, saying she simply saw a travel agent deal too good to pass up.

“I should have known; she has always been an interfering old bat,” the bride-to-be said, adding that now she and her fiancee are looking for alternative locations for their honeymoon.

Mumsnet users were quick to jump to the defence of the bride, with one asking, “That’s incredibly weird. Who crashes their son’s honeymoon?!!"

Another asked, "Does she always have boundary issues? Definitely find a new resort, not your problem if she is upset.”

One user joked, "Ooooh, maybe she'll wear a wedding dress on the day too!" while another suggested not changing any of the plans at all.

"I'd be telling your fiance to tell his bats*** mother to cancel her holiday or they'll be no wedding. Put your foot down now or this craziness will continue forever."