The 57-year-old actress - who met the musician when he was still married to first wife Frances Tomelty - believes the "tough talks" she and her husband have regularly are key to their relationship lasting for over 30 years.
She said: "Of course, we've had some bad times in 30 years. We've needed to have tough talks - those tough talks that couples don't have often enough - those talks that couples don't have often enough.
"Rock 'n' roll couples are meant to behave very badly and there has been some bad behaviour. But there's also been some great levelling and some, 'All right, we'll make things work by this new agreement'."
Trudie - who has four children, Bridget, 27, Jake, 25, Coco, 20, and Giacomo, 15, with the star - explained the couple have now promised to "honour and value each other", insisting their problems don't stem from adultery.
She added in an interview with The Times newspaper: "It wasn't specifically infidelity, just behaviour that we've agreed now should be different, that we should honour and value each other more. One assumes infidelity. One assumes that's the obvious thing. But couples hurt each other in myriad ways."