Whether you’re expected to make yourself scarce during access visits, find yourself getting reluctantly embroiled in the school run or have to miss out on expensive holidays because he pays so much in child support, it soon becomes clear that you are not the only love in his life.
When on-off couple Sienna Miller and Jude Law announced their breakup at the end of last year, a friend of Miller admitted that she found it difficult to cope with the fact that his children were the centre of his world.
This rather merciless mode of operating is one being exploited by internet entrepreneur Howard James who has enjoyed huge success catering for niche markets.
As well as attracting sex-hungry men and women online he has set up websites for a curvy clientelle and even one for the aesthetically challenged."It's a sad fact that up to half of the United Kingdom is made up of ugly people," he said.
They include uk for older people, uk for single mums and dads, and gay people have their own websites such as which has six million members from around the globe.
The most notorious, however, has to be which is infamous for ejecting members if it's felt they don't meet their exacting aesthetic standards.
But for some people there is a deeper, more serious side to making an online match.
"And it gives the women more choice as well, so you put yourself on there and they can approach you."Because I converted to Islam I don't have the same network of family and friends which could introduce me to a suitable wife either, which made things difficult."And if I were to approach a woman in real life it would also be awkward. And how do you know if someone is already married or not?
• Downfall of an It-girl• Why I don't want to meet my birth mother• Winstone's wild child Rebecca is deeply in love with the man of her dreams. During the week she lives at his flat, but come Thursday night she obediently tidies away her toiletries from the bathroom, packs her clothes into a bag and removes all traces of her existence - before his children arrive.Adeem Younis first thought of creating a very specific site when he was a student at Leeds University.