In "Sky Flakes Keep Falling on My Head", a vacation has Gone Horribly Wrong and the couple sit on a mountaintop with snow falling. Mindy cannot move because of her hurt ankle, but she urges Mork to try and make it down the mountain by himself, asking, "What have you got to lose?" Mork's response, one word: "You."
The conclusion of "Mork's Mixed Emotions," just before Mork's emotions reintegrate as his whole personality, Mork give Mindy a kiss as each of his emotions in appreciation of her love and help.
Mindy: Mork, when you entered my life, you brought me happiness, joy, and laughter. My love for you transcends time and space. Grow old with me, the best is yet to be.
Mork: Min, you're my friend, you're my love, you're my life. There's supposed to be more, but that's when the lady in the card shop said "Buy or get out!" I don't know the right words. In fact, I don't think they're enough to describe how I really feel about you. Love is a small word, but I think it covers so much. I love you.
From season 1: Mindy telling Mork about Christmas.