Charles and I were at a party recently when an acquaintance of his, Steve, started talking about a woman he'd slept with on a first date and described her as "a bit of a slut".

I went nuclear. While I don't agree with calling anyone names, by his own logic he'd been a "slut" as well.

"Men are programmed to spread their seed," he said, "but women should be monogamous because they can only produce one egg at a time."

He mentioned a study that apparently revealed "evolution has not adapted women to having casual sex" because some women reported feeling "used" afterwards. I think women would feel less remorse if there were fewer idiots like Steve out there. Even Darwin knew females weren't monogamous.

Professor Tim Birkhead wrote in his book Promiscuity: An Evolutionary History of Sperm Competition and Sexual Conflict that Darwin was aware of instances in which females received sperm from more than one male. But Darwin, being a Victorian, preferred writing about promiscuity among plants than human females. Sleeping around may benefit women because of sperm competition – even if that involves sex with several different men in quick succession.

Men do flirt with me more when I'm in a new relationship. I thought that was a reaction to my exuding confidence and happiness. But maybe there's something more primal going on. Biologist Olivia Judson writes that men shown explicit pictures of a woman with two men (potential rivals) produce a higher proportion of swimming sperm than men shown explicit pictures of three women.

I unintentionally had a chance to test the love-rival theory when I met Charles in town for a late lunch, which ended with us polishing off two bottles of wine and slipping back to his flat to eat dessert off each other. With no time to shower, I emerged, legs still shaking, en route to my next meeting. I met my TV producer friend for coffee, and he was very flirtatious, and asked if I'd changed perfumes. That afternoon, five men gave me their phone numbers. I binned them. I'm choosing to be in a committed relationship. Love is more than an evolutionary arms race.

But being monogamous is a choice for both sexes, because at the end of the day we all have animal instincts. Maybe fear of being judged is also part of evolution. I read recently researchers found that female chimps wanted sex with as many males as possible without other females finding out. Hmm.

The row with Steve hotted up when he used the word "whore". I "accidentally" dumped a glass of red wine all over the crotch of his very expensive suit. I felt horrible afterwards. The bottle cost £23.

Belfast Telegraph