After returning home from Billie's cremation in next Tuesday's edition of the Walford soap, Carol finds herself comforted by her late son's best friend Connor before heading to bed with him, despite the previous ill-feeling between the pair. The plot twist was first revealed at the weekend.
Speaking to Inside Soap, Coulson admitted: "Carol's crossing a major boundary because Connor was Billie's friend in his gang, so she hated him. But she feels she's got nothing left to lose at this point."
The actress continued: "It's very primal. I thought 'Whoa!' when I read the scripts. I have an 18-year-old daughter, so for me it's like, 'Don't go there, Carol!'.
"For her, though, this is a brief moment where she doesn't have to think about Billie's death. It's not even lovely sex - it happens in a fit of loss and grief."
Coulson recently said that she is keen to see Carol develop more friendships on Albert Square in the aftermath of her devastating loss.
> Click here to read full spoilers for next week's EastEnders episodes