McGarty, who plays Whitney Dean on the soap, confirmed on Twitter at the weekend that she had broken up with her former co-star.
She gave no reason for their separation, saying only that it had "nothing to do" with his professional partner Brianne Delcourt.
In an interview conducted before their split, Lapinskas hinted that his time on Dancing on Ice was creating problems.
Asked if McGarty was jealous of him getting up close to Delcourt, the Anthony Moon actor told Now: "No, she's taken it all in her stride... Shona would only be jealous of the time it takes me away from her, as the show can take over your life.
"So she's not jealous of Bri, just the time I'm not spending with her. But things have got better now and she's proud of how far I've come on the show."
Photo gallery - Dancing on Ice show 9:
Lapinskas also noted that McGarty had been spending "a lot of time" with their EastEnders colleague and his former on-screen brother Tony Discipline, but was confident that "nothing will ever happen there".
Despite the claims from McGarty and Lapinskas, the actor was photographed apparently holding hands with Delcourt following Sunday's (March 3) Dancing on Ice show.
Lapinskas will compete against Olympians Beth Tweddle and Luke Campbell in this week's final.