Every letter, every phrase should offer delight. Getting back to the animals business, it sounds like you're portraying the couple as two animals. They examine their fingers under gloomy light as gorillas might under jungle canopy. They roar with fury, they show their teeth. It adds to the vivacity of our own self-perceptions.
People have hot little cheeks, they do scream and snarl.
People are like characters in a zoo. There's a great phrase I cherish that was written by a young boy I worked with in New York City. By the way, the couple in this poem does not represent people I ever really knew. They're literary characters I remember vaguely from something I read once. I just gave them a wacky twist.