When writing an engagement card, its important to congratulate the couple on their engagement and express your excitement for their future together. Here are some tips and ideas to help you write a heartfelt message:

• Add a personal touch: Include a memory or inside joke that is unique to your relationship with the couple.
• Keep it positive: Avoid negative comments or anything that could be interpreted as criticism.
• Share your well-wishes: Wish the couple a lifetime of love and happiness, or use a quote about love and relationships.
• Be sincere: Speak from the heart and let the couple know how much you care about them.

Here are some examples of engagement card messages:

• "Congratulations on your engagement! Wishing you both a lifetime of love and happiness."
• "So thrilled to hear your wonderful news! Congratulations on your engagement."
• "Congratulations to my favorite couple! Cant wait to see what the future holds for you both."
• "Wishing you both all the love and happiness in the world. Congratulations on your engagement!"
• "Congratulations on your engagement! May your love continue to grow stronger with each passing day."

Remember, the most important thing is to write a message that feels genuine and heartfelt to you.