'Too much love will kill you' - Brian May, but only of course if you are leaving for someone else.
I strongly suspect 'I want to break free' - Queen is in the right sort of vein. I had been trying to think of something folky, I guess the best brush off is probably 'as I roved out on a bright May morning' (is that the title?) 'If I married the lassie who had the land my love, it's that I'll regret for all my days.'

But for real delicacy, you just can't beat guns and roses 'I used to love her, but I had to kill her' (I had to put her six feet under but I can still hear her complain.)