Nothing tests a relationship like traveling together. And apparently, this couple failed.

Footage allegedly captured on an airport shuttle bus shows a man and woman getting into an argument that escalated into a fistfight. It was not immediately clear what started the altercation, but the two were reportedly said to be in a relationship with each other.

new couple fights shuttle bus

The couple appeared to be intoxicated during the incident, according to a witness. (SWNS)

The fight occurred on a shuttle bus at Alicante Airport in Spain, The Sun reports. The travelers had reportedly arrived at the airport on a Ryanair flight from Birmingham in England.

The couple also appeared to be intoxicated, according to witnesses.

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“I just thought to myself, 'Oh, here we go,' said a fellow passenger who spoke with South West News Agency (SWNS) about the incident. "We think that they had gotten drunk on the flight over to Alicante, and then things had just exploded on the shuttle bus.”

Couple fights on airport shuttle bus 2

Witnesses were unsure what sparked the fight, but during the incident, the couple could be heard hurling vulgar insults at each other. (SWNS)

The witness added that she wasn't sure exactly what started the altercation. "I think they were having a domestic [argument] that got so heated it became violent, and that one of them just touched a nerve — I think she lashed out first. We have no idea what they'd argued about, but when it kicked off, things escalated so quickly we couldn't imagine what had been said.”

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As seen in footage of the fight, both participants appeared to be throwing punches at each other.

"At various points, one or the other was on top of the other, punching them in the head, and people intervened to break it off. I mean, they were really going for it — landing proper punches at each other," the witness said.

Footage also shows fellow passengers shouting at the couple to stop, and at least one other woman trying to intervene to pull them apart,

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Following the fight, the couple was detained on the bus until police arrived, The Independent reported.

A representative for Alicante Airport was not immediately available to confirm if the couple was charged.