1. 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. With Christmas coming, a spot of “no strings” sexual solace in the arms of your ex starts to seem like the solution.

2. 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.

3. And it's so much easier than starting something new. There's a comfort level that comes with knowing someone really well that new relationships just don't provide.

4. Cue the violins. Instead of remembering all the reasons you broke up, you start fantasising about her soft, warm body up against yours. And before you know it you have convinced yourself that you can overcome any residual anger or upset and selflessly help each other through the night.

5. Next comes 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.

6. Safe sex is now an issue, too. It's difficult to admit to having had sex with someone else, so even if she promises you that she has been celibate since you split, you will need to use condoms just in case.

7. 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 is that it sends mixed messages to your ex and is likely to leave you feeling very confused too.

8. 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.