According to Confidential, a source close to the former couple revealed made the relationship-ending move on a boys night out.
“He was out with the lads and hooked up with a 19-year-old girl,” the insider said.
“He is in his mid-‘30s and he is still making stupid decisions like this.”
While either of them is yet to respond to the claims, Luke, 33, did take to Instagram to make a public apology on April 17.
"Hey guys, sorry it’s taken me a while to update you guys on Lisa and I..." he began.
"It’s obviously been a tough month or so. You know I struggled making that decision with Lisa and we did try and make it our on the outside, get into a debate around he said she said and all the different reasons that lead to how things broke down. Out of respect for her, I think it’s just best to say that I stuffed up and I’m sorry.”
"I feel like I’ve let a lot of people down, my friends and family and all you guys and obviously Lisa. I hope that you guys can understand somehow the pressures these situations can cause and that we all make mistakes."
Meanwhile, when WHO spoke to Lisa, 31, she kept tight-lipped about the situation and confirmed she's remaining positive about love and focussing on her business.
"We kind of spent nearly every day together when we first came out – we were in a little bit of a love bubble," she recounted her steps after the two chose to exit the show.
"We were really happy and we were doing a lot of different things together but you know it’s kind of out of my control… It’s hard. You know we did date for a couple of months and then we broke up for certain reasons. Yeah, I’m kind of in a position where I’m happy and moving on."
"I think people just make mistakes and that’s what’s happened in this case – obviously, there are rumours out there and I won’t go into too much detail – I think people know where they make mistakes and they, unfortunately, in this case, it didn’t work out in my favour.
"I’m alright [now], I’m a very happy person. I keep myself busy with my job."