Tyldesley, who plays Eva Price on the soap, began dating Sam Witter early last year.
Witter, who is 22, is seven years younger than the actress.
A source told The Mirror: "They have busy work schedules and weren't getting to spend much time with each other.
"They have just grown apart. The age gap was a bit of an issue because they want different things.
"Cath is at a stage where she wants to settle down and Sam is still only 22 so he just isn't ready for that kind of long-term commitment.
"It was a mutual decision to call it a day. They will remain friends and plan to continue training with each other, though that is going to be difficult, especially when the split is still raw and causing pain."
Tyldesley and Witter own a company together, Dream Partners Limited, and had planned to bring out fitness DVDs and exercise books this year due to Tyldesley's five stone weight loss.