There's nothing quite like having the wind in your hair and your favorite person alongside. Recreational biking allows you to explore paths around your city or town. If you want to feel more productive, run small errands on your bikes or cruise to a dinner date or picnic in the park. You'll not only stay in shape, but save a little money on gas. As more cities become bike friendly, it's an opportune time to dust off the ol' bike and hit the streets.
If you want to increase the togetherness factor, rent a tandem bike and see how what it's like to have four legs pedaling, but only two arms steering. Now that requires trust.
Next, how can you go wrong with a sport that uses the word "love"?