Gordon Fleming is, by his own account, an environmentally sensitive guy.

He bikes 12 1/2 miles to and from his job at a software company outside Santa Barbara, Calif. He recycles as much as possible and takes reusable bags to the grocery store.

Still, his girlfriend, Shelly Cobb, feels he has not gone far enough.

Ms. Cobb chides him for running the water too long while he shaves or showers. And she finds it “depressing,” she tells him, that he continues to buy a steady stream of items online when her aim is for them to lead a less materialistic life.

Mr. Fleming, who says he became committed to Ms. Cobb “before her high-priestess phase,” describes their conflicts as good-natured  mostly.

But he refuses to go out to eat sushi with her anymore, he said, because he cannot stand to hear her quiz the waiters.