An ex colleague. He was separated from his wife, with whom he had a young daughter, who he was having real issues accessing. We all sympathized with him as he had had to move back into his mum's house following the split, to raise the money to pay legal fees for access.
Months later, we started seeing each other. All good.
Until his wife phoned me at work. She wasn't an ex at all. He lived at home with her and his DD and left his wedding ring in the car every day. So he hadn't only lied to me, but all his colleagues too.
Worse, his wife told me he had done this before. Told her he had a job working away during the week, and shacked up with someone else. The OW thought he worked weekends with days off in the week.
And his wife STILL took him back! He left our employer soon after, having taken a week off with a "back injury". I had (helpfully) managed to give the boss advance notice, about the planned back injury though, the week before, so work wasn't too in the shit.
Last I heard, he and his "ex" had moved house for a "fresh start" 