Q. One of my mates’ girlfriends is cheating on him. We’ve tried to tell him but he won’t listen. What should we do?

Reuben says: Some people can’t help themselves and don’t want to be helped – I know, because I’ve been there.

I once worked in a sandwich bar and fell madly in love with one of my colleagues. Her name was Alexandra and I never had a chance; she was a bubbly 19-year-old and I was a 34-year-old sandwich composer.

But every morning, I would leave elaborate, audacious sandwich designs in the cool room, dedicated to her, in the hope she would one day discern my true feelings.

It culminated in the ‘Alex-sandra-wich’, with extra (broken) artichokes hearts and several drops of my own blood. The owners fired me. I never saw Alexandra again.

Your friend has ordered a heartbreak baguette with lashings of humiliation and self-loathing, but designing your own sandwich is what grown-up life is all about.

Dear Ruby

Ruby says: The short answer is that you need evidence of her infidelity.

I did a stint as a deep cover operative in Ciudad Juárez – the epicentre of the Mexican drug war and the narcotics capital of the world.

My brief was to build a case against one of the city’s most violent syndicates. I got a job in one of the strip clubs they owned and hooked up with one of the main men.

I was in so deep I forgot I was a cop; I only left because a rat in my unit blew my cover. My mark tried to gun me down at his villa but I drew first and left him to bleed out in his swimming pool.

Basically, you need to bed his missus and create some record of it. Once you do that, make sure you blackmail her – cash in return for your silence – but then shop her anyway. That’s how the streets work, amigo.

» Got a sex or relationship worry? Email dearreuben@tntmagazine.com