Dear [Names of Newly Weds]
I would like to express my happiness for you both as you start a married life. I am really glad that the two of you ended as a couple.
There could be difficult times in the coming years of your married life. But I know you can pass through everything after being together for almost a decade. Your marriage, I know, is just a formality of your endless commitment and love for one another.
As you start to build your own family, I hope you would not set aside the friendship that you have built even before you formally became lovers. Hold on to one another every time a storm comes your way. Love is not the sole ingredient you should include for a marriage to work. At this point, I know you already know the importance of trust, honesty, and loyalty.
I wish you all the best.
[Name of Sender]