But she is an old hand at this type of encounter and tells me she's met many men through the site, and that I was probably the only one who hadn't lied about my age.
"Sophia" tells me she thinks relationships have a shelf life of about ten years before boredom sets in, but that she stays married to ensure her children have a stable home.
What I don't know is how her husband will feel about it. Aside from the little matter of her marital status, she also believes I have a wife, but she doesn't care.
She wants instant gratification even though we've exchanged only a few words online.
In order to fit in with the general ethos of the website I have invented a wife.
Our relationship, I note, has suffered because we don't spend enough time together (not surprising really, since she doesn't exist).
But if I'm going to find out what really makes these women tick, I need to leave the safety of the virtual world and see them for myself. I arrange to meet a 41-year-old mother of two who misses "romance and flirting", in a cafe in two days' time.
She has declined to tell me her name, so I have to think of her as her web sobriquet.
It may sound like an unpleasant niche website for a handful of amoral people to whom wedding vows never meant very much.
But it claims to have more than 100,000 members in the UK.
Many of them are middle-class, many have young children.