She still loved him, but his constant nitpicking started to enervate her. The word enervate can be used as a verb or an adjective.

The elderly man didn't participate in the marathon because he knew it would enervate him.

I will enervate and destroy my opponent.

Shouted abuse from the fans could easily enervate a professional sports player.

The speech was so uninteresting it began to enervate anyone within a five-mile radius of the podium.

To weaken or deprive of strength.

He made her body enervate into a couch potato. This sentence works because the word means to cause someone to feel weak.