Sabotage

sabotage
verb, transitive. To deliberately destroy, damage or obstruct something, especially for political or military advantage. Also a noun.

Rain was pelting the street and sidewalk when Frank arrived at Missy's apartment. He took advantage of the deluge to spend a little time reflecting on what he was about to do. The relationship had been going well ... too well. It was time to sabotage it before it was too late to walk away.

If he crouched a little, he could see Missy's windows on the top floor. Every one of them was alight. She was probably in a frenzy of cleaning. He liked that about her, but still....
The first time he had escorted her to her door and gotten a look inside, the place had been a pigsty. He should have heeded that red flag, but he hadn't been able to resist her physical charms. He knew she had gone all domestic after their first tryst, hoping to ensnare him in an engagement, soon to be followed by marriage. The second time he had accompanied her to her apartment, she had invited him in without hesitation, for the place was spotless. He felt glum as he remembered it. Other than her slovenly housekeeping, Missy was perfect, or nearly so. He couldn't settle for less than perfect, though. He knew that as soon as he made a commitment, her facade was going to slip, and if he married her, it would drop away. Never again would she rise to such heights of cleanliness and tidiness, and he couldn't abide a dirty home. He simply couldn't.

The rain continued to fall, more heavily, if anything. He suddenly had an idea and rummaged in the glove box. Yes! He had left the last pack in there when he quit. He fished out one cigarette and sniffed it. It would taste stale, but it would do. He cradled it between index and middle finger as he pushed the lighter in and waited for it to pop. Entering Missy's place reeking of cigarette smoke was certain to be a relationship-killer. She ranted against smoking every time she caught even a faint whiff of that odor.

Definitions adapted from The New Oxford American Dictionary, Oxford University Press, Inc., 2005 (eBook Edition, copyright 2008), and from Webster's Seventh New Collegiate Dictionary, G. & C. Merriam Company, Publishers, Springfield, Massachusetts, USA, 1965, depending on which is more convenient to hand.