A woman who invited her friends on her anniversary trip ultimately ruined her boyfriend's plan to propose to her, resulting in the end of their relationship.

Sharing his story on Reddit, the woman's boyfriend explained he had been dating "Sarah" for five years.

They had enjoyed several vacations together as a longtime couple, but their most recent trip was mean to be special. The man was looking forward to spending one-on-one time with Sarah in Colorado, and had plans to pop the question at the end of their romantic trip.

However, a few days before the trip, Sarah informed him she had invited her two best friends along without consulting him first. Though he was annoyed, the man agreed, hoping he would still get some alone time with his girlfriend.

Unfortunately, the romantic getaway quickly turned into a girls' trip.

"Sarah essentially blew me off for her friends, and we didn't get any private time ... After three days of being in second place, I decided to leave the trip and head home," he wrote in his post.

Once Sarah returned home, he tried to have a discussion with her.

"The first question I asked Sarah was how she thought the trip went. She said we all had fun and it was memorable," he shared in a follow-up post.

The man explained to Sarah why he was upset and gave her examples of various times he felt like the third wheel in their relationship.

"I signed up for a monogamous, not poly, relationship," he explained.

He also asked Sarah if she had any idea he was going to propose to her.

"Sarah said she didn't know at all ... She claimed that she wouldn't have invited her friends to come along if she knew, but I responded that it would ruin the surprise if I told you," he continued.

"Sarah begged me to stay with her and believes we can work everything out. She didn't want me to throw five years away after this one bad trip," the man added.

Though Sarah was hopeful they would be able to work through their relationship issues, the disastrous trip helped the man realize there wasn't "enough room" for him in her life.

Ultimately, the couple broke up.

"I left Sarah in the house by herself, and I drove off to my friend's place. I'll figure out how to get my name off the lease, and I'll plan to get the rest of my belongings ... As for the ring, I will return it this weekend," he concluded.

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