The 55-year-old revealed he thinks his fellow Britain's Got Talent judge will work things out with his wife.
Speaking to HuffPost UK, Simon explained: "I said to him, 'you're not the only person in this situation.' That's a cliche thing to say but it's true.
"Don't feel sorry for yourself. It's bad news and I feel bad for him but he has to carry on with his life.
"She's a nice girl… they'll work it out."
Earlier this month it was reported David and Lara had separated after five years of marriage. They share 22-month-old son Alfred.
When rumours of a split first broke, a source told The Sun: "David still hopes it is a blip and that they can get the marriage back on track somehow, especially seeing as there is a child involved. He is still fiercely protective of Lara."
Both David and Lara have remained silent, with neither one of them confirming rumours of marital problems.