The actor, who plays Steve McDonald on the ITV1 soap, started dating Emma at the end of last year after they met at a Christmas party.
"Everyone knew Simon was madly in love but the news came out of the blue," a Corrie source told The Mirror. "He has decided not to hang around. He wants to have a wacky, laugh-a-minute do with karaoke. Plenty of cast pals plan to come along."
Gregson was found guilty of drink-driving earlier this week.
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