Experts say that camaraderie between former lovers is like playing with fire and can take a toll on your current and future relationships.
With online social networks becoming more and more integrated into our real lives, former partners are more of a problem than ever because of websites like Facebook.
Author and relationship expert John Aiken said it was fine for single people to have their ex as a friend on these sites. But, when one begins a new relationship, he or she needs to tread carefully, he warned.
"You need to consider how much contact you have with them, the type of intimate details you exchange, and the type of photos you share with them," News.com.au quoted Aiken as saying.
"If you're in this position, set some clear boundaries with your ex and put your new partner first at all times.
"If that means shutting down your social networking with them, get it done today and make your new partner feel important," he added.
Clinical psychologist Sally-Anne McCormack said being friends online with an ex had hidden pitfalls.
"The reason it may not work is because, while one of the partners is happy to stay friends, the other one may have hope that the relationship will be renewed at some stage in the future," said McCormack.
"Staying friends with an ex can work for some, but there needs to be some caution for both parties. If staying friends is preventing someone from moving on, then it is not healthy," she added.