It’s not the number of words that counts, but the caring behind them. If the card has already said it all or you’re just not in a gushy mood, it’s fine to keep your personal message short and sweet.
- “Wishing a perfect pair a perfectly happy day.”
- “Here’s to another year of being great together!”
- “Anniversary cheers!”
- “Happy [21st] anniversary, you old lovebirds!”
- “Hope you find time to look back on all your sweet memories together.”
- “Always knew you two had something special.”
- “Hope the next  years are even happier than your [first decade] together!”
- “Can’t believe it’s been [three] years already. Here’s to many more!”
- “Love and much happiness to one of our all-time favourite couples!”
- “Warmest wishes to the wonderful two of you on your [sixth] anniversary.”
- “Wishing you a happy ‘you two’ day!”
- “Another year, another great reason to celebrate!”
- “Congratulations all over again!”
Writing tip: If the card you’ve chosen already has “Happy Anniversary” printed on it, you can add an ellipsis […] and a little something after it: “…and many more!”, “…with love to you both.”, etc.