• Your relationship wasn't working so you split up. But your split-up isn't working too well either. You are single, miserable, and surrounded by irritatingly loved-up couples and ever-so-happy families, so a spot of 'no strings' sexual solace in the arms of your ex starts to seem like the solution.
• It's certainly cheaper. No need for expensive dates or elaborate mating rituals. A bottle of Cava and a bunch of garage forecourt carnations always did the trick before.
• And it's so much easier than starting something new. There's a comfort level that comes with knowing someone really well which new relationships just don't provide.
• Cue the violins. Instead of remembering all the reasons you broke up, you start fantasizing about her soft, warm body up against yours. And before you know it you've deluded yourself into thinking that you can overcome any residual anger, or upset, and selflessly help each other through the night.
• Cue the reality check. Sex with your ex might relight your fire, but all the baggage that brought you down will still be there in the morning.
• Safe sex is now an issue too. Even if she promises you that she has been celibate since you split, you'll need to use condoms just in case.
• Question your motives. Sometimes people go back into old relationships because it's an easy way of affirming that they are still attractive. The problem with that is it sends mixed messages to your ex and is likely to leave you feeling very confused too
• And question her motives too. Women rarely resurrect a sexual relationship with an ex partner with the express intention of keeping it casual, so if you don't want to get involved with her again don't go there.
• If you do want to get back with her, you'll need to work out what went wrong last time first. You can access a relationship expert face to face, by email or by phone at Relate (www.relate.org.uk / 0300 100 1234)
• Sex with the ex seems simple, but is actually very complicated. Samantha Jones from Sex and the City summed it all up when she said "Sex with an ex can be depressing. If it's good, you can't get it anymore. If it's bad, you just had sex with an ex."