Good sayings for a Valentine's Day card express adoration for the recipient, such as, "You mean so much to me and I love our time together." Adding a quote about love is also appropriate, such as this unknown author's quote: "Every love story is beautiful, but ours is my favorite."
When the relationship is new, it's better to avoid comments of a sexual nature or unnerve the recipient by expressing love too soon into the relationship. Safe comments are best, such as, "I love that we are spending this special day together." For a long-term relationship, a Valentine's Day card is a way to share intimate thoughts. For example, one could write, "I cherish every Valentine's Day that we have spent together, and I can't wait to create new Valentine's memories with you tonight." It's also a great time to add more emotional quotes, such as Robert Browning's, "Grow old with me! The best is yet to be."
For a spouse, a Valentine's Day card should show appreciation for everything they do and are in the relationship. It is acceptable at this relationship level to be a little sappy. For example, say something cute and endearing, such as, "I love everything about you and I always will, especially your cute butt." A funny quote about love and marriage can be even more effective, such as Rita Rudner's, "I love being married. It's so great to find one special person you want to annoy for the rest of your life."