I watch the two sharks glide through the aquatic blue. Side by side they curve between false coral and effortlessly swerve retreating sea creatures. A small pilot fish swims behind a meter away. It copies every movement and dodges the kicked-up debris remaining in the shadows, unseen.

Three weeks into a trip through northern Spain, the San Sebastian Aquarium is to be a distraction from my current predicament. In the reflection of the toughened glass I see my companions Don and Kate holding hands and watching an eel devour a baby squid.

They are my sharks. I am the pilot fish. Don and Kate are a couple, and I am the dreaded third wheel. It is a position of unrelenting and inescapable awkwardness.

Third wheels are never beneficial to relationships of any kind. Just look at Yalta. Churchill and Roosevelt palling around and leaving Stalin out. We all know how that ended. Third wheels cause wars.

This situation is not of my doing. I had planned this six-week trip with Don as a relaxing (read drunken) post-graduation break. Meanwhile, his ailing relationship with girlfriend Kate took a turn for the worse. Instead of just having a baby like everyone else, he invited Kate on a month and a half holiday with some guy she’d never met before (enter your protagonist). Surprisingly her answer was yes. This is how we ended up here, skipping between ever-smaller hostel rooms with an ever-increasing sense of unease.

There is nothing like spending 24/7 with someone to expose your fatal differences. Instead of righting the ship it capsized spectacularly, spilling its cargo of bitchiness and melodrama all over my holiday.

We’ve travelled through Basque Country, eating, drinking, and generally over indulging. We’ve played pelota with locals, seen some fascinating art, and even watched a man punch a racehorse. All the time sharing a room, sometimes with one double bed where I’ve curled up like a pet dog in sheets and blankets on the floor.

I’ve learnt a lot from the experience. Like the fact that most pavements are not wide enough for three people to walk side by side, and that relationships founded on in-jokes are not conducive to third-party involvement. On the up side, there are opportunities for stealing food whilst your companions are distracted by each other’s ‘endless blue eyes.’ There are also the hostel owners, barmen, and one fake-Rolex salesman I have befriended whilst trying to create space for the happy couple. Despite my distraction attempts there has, thus far, been little alone time available for the couple.

On our arrival into San Sebastian I realise that if I am to be the ultimate good guy and make myself scarce, this is the city to do it. And what a city! The seafood, the cafes, the art, the people. The beachiest beaches and the sunniest sun! It is undoubtedly a city of romance. Of real, old-school, historic romance. It is sun-bleached images of Audrey Hepburn strolling the promenade in bug-eye shades and black-and-white lovers dining on ocean views. You know, proper movie-romance shit.

I decide to disappear and leave it to them to mine this city for all its romantic gold.

My idea is brutally thwarted on the first evening. Amidst a glut of pintxos and vino blanco in crowded street bars, something goes wrong. Instead of distancing themselves from me, the strange extra appendage of the evening, the distance appears between them.

I realise that far from being a wedge between them, I have in fact been the glue.

I am swiftly promoted to the position of reluctant mediator as the trip becomes a back and forth of sideswipes and snarky quips. Necessity makes me a psychologist as I negotiate for my holiday.

I begin to see them separately more often and start to consider an alternative career as an agony aunt. On the third day in the city Don and myself make the trip around the coast to see Chillida’s Wind Comb sculptures. As we look at the ocean framed through rusted steel claws, he receives a simple text from Kate:

“We need to talk.”

“It is about time we sorted this out,” he says to me. But his face doesn’t seem to believe what his mouth is saying. He walks away amidst the elements, amidst the thunderous waves and the twisting corroded monoliths of Chillida’s sculpture and the scene seems perfectly set for a showdown.

When I meet them that night in the bar their faces are cast in counterfeit smiles. I feel like a kid whose parents are going through divorce. They want to spare me the anguish. After all there is only a day left. Kate will be leaving us tomorrow. There is nothing like spending 24/7 with someone to expose your fatal differences. Instead of righting the ship it capsized spectacularly, spilling its cargo of bitchiness and melodrama all over my holiday.

We wave Kate off from the airport, all fake hugs and smiles, and return to the city and to our adventure. I see the sadness written on Don’s face. Again the responsibility falls to me to rescue the trip. The show must go on. There will be no sleep tonight. After all, sharks must keep swimming to stay afloat.