Rumours about the relationship started to circulate earlier this year when the date for their wedding was pushed back and Lisa also took a trip to New York without Gerald.
They were engaged in 2009 and spoke subsequently of how in love they were.
Speaking earlier this year, Dublin Housewives star Lisa brushed aside talk that all was not well in the relationship.
"We're not split up," she said. "Not at all. Everything between me and Gerald is certainly nice and strong."
Lisa, who has been engaged three times, previously talked about her hopes of starting a family with Gerald. And the lawyer to the stars shared her hopes for children.
"I would love to have children with Lisa," he said.
The Dublin woman was a long-time girlfriend of Lord Of The Dance star Michael Flatley and she was once engaged to boxer Joe Egan.
But a source close to beauty salon owner Lisa said friends were aware for a while that a split was on the cards.
"We all knew there were some issues, all of their friends are supporting them," said a source.
"In fact a few of us got together this week and we agreed we wouldn't talk about it publicly. We'll all be there for her."
It's been a testing year for Gerald and Lisa.
In May 2011, Lisa was held at knifepoint as four masked robbers broke into the couple's Brittas Bay home and stole her jewellery. The experience was particularly traumatic for Lisa, who was said to be in a "terrible state of shock" for weeks afterwards.
At the time, Gerald said that the robbery had slowed things down on the wedding front.
"To be honest, the robbery set it back," said Gerald.
"It's tough because we had the perfect ring picked out and now we're trying to pick out another one, which isn't easy in this day and age.
"The wedding has gone back to next year. We have a lot on particularly with the robbery, we need to replace the ring."
But Gerald never got round to buying a new ring and, sadly, the wedding will never take place.
Lisa and Gerald got engaged in 2009 in the Residence private members' club.
Apparently friends cheered and champagne corks popped as the two spoke of how in love they were.
The wedding was tipped to be the celebrity event of the decade.
Gerald and Lisa were known for throwing extravagant and glitzy parties. Earlier this year, Gerald bought Lisa a sports car and invited 160 friends and family to celebrate her 40th birthday.
Gerald also told hundreds of thousands of viewers on the Late Late show how smitten he was with his fiancee.
The two had always publically proclaimed their love for each other making their split all the more poignant.
Theirs is the second high-profile split to have emerged this week.
Operation Transformation host Kathryn Thomas (33) split with her garda boyfriend Enda Waters of five years.