My girlfriend called me one evening, during the period when her husband was struggling to quit smoking, and confided that she was seriously considering renting an apartment of her own, because living with him as he made the transition was pure Hell. He was crabby, irritable, irrational, demanding, mean, on and on. (That's what she told me, anyway.)
But he stuck it out, it's been the better part of a year, and they are now living happily together in harmony.