Most people would get jealous of a third party barging into their relationship, but it's another level of ick if it's the person's sibling you're competing against.
One woman has revealed how her ex-boyfriend's affectionate bond with his sister became a bit too much, leading her to call the relationship off. As you would, really.
30-year-old Jacinta Coelho, from Sydney, Australia, told the Mail she ditched the bloke - renamed as 'Jack' to save him embarrassment - after just four months because his sister proved to be more than just a third wheel.
Jacinta met Jack at a pub years ago and quickly hit it off before he introduced her to his family a month later. And that's when things started getting weird.
Writer Jacinta said she found it 'odd' how often Jack would give his sister compliments about her hair and how she was dressed, before 'Melinda' and her brother seemed uncomfortably attached.
"We would go out and she'd be there nine times out of ten. It seemed like she didn't have her own friends," Jacinta said.
"Jack and I might get a few hours alone but she'd always come into it somehow. If there was any excuse to be there, she'd be there.
"It almost starts to feel like you're competing with someone you're not meant to be competing with - it felt like she was cutting my grass."
Jacinta bit her tongue at first as things were going well with the guy, before things started getting too bizarre for her to ignore.
One encounter Jacinta has mentioned is having Melinda stare at her from a distance while she snuggled up to Jack on the couch.
Other weird incidents included Melinda telling Jacinta that she was still single because no one would ever be more suited to her than her brother, and Jack even putting his arms around his little sister's waist while they were cooking food.
But then, according to Jacinta, the worst was yet to come, as she stumbled upon Melinda sleeping in Jack's bed one night.
"I was going to stay over, so I went into his bedroom and was trying to set up and she was asleep in his bed," Jacinta said.
"It was the straw that broke the camel's back... I had to walk out of the room and ask Jack why she was there."
"He said: 'She does that sometimes. Sometimes she gets creeped out in the other room,' like it was normal.
"She was 21, it's not like we were talking about a two-year-old."
Jack didn't like being confronted about his rather dodge relationship with his sister, leading Jacinta to dump him after just one more date.
Thankfully Jacinta eventually found the right person for her, and was married in 2016. Looks like she dodged a bullet there.
They say loving your family is important and all, but maybe this guy and his sister were taking that advice a step too far.
Featured Image Credit: Warner Bros. / Friends