Simply replace the unfilled areas such as "" and "[date]" with your information.
I know that [you/we] are having a difficult time with [event or difficulty]. That being said, I need you to realize that this will eventually pass. One day, we will look back on it and be glad we got over that hurdle together. Remember that word, together. After all, it is only [source of difficulty]. That has nothing to do with how I feel about you and how you feel about me.
There are some difficult decisions that have to be made. Darling, you are a [adjective] and [adjective] [man/woman]. I know you will make the right choices. I have faith in you. I believe in you and you need to believe in yourself. If you could see yourself the way I see you, you would never be in doubt. You have my whole heart and you know I wouldn't give that away to someone who didn't deserve it.
I love you,