And if you say the word, I could stay with you
What Sherlock thinks is, On the day I die, be it in a dirty alley at forty or in my bed at eighty, the last thing I will remember is tonight, the way you looked at at me on the snowy pavement, cheeks pink with the cold, breath puffing in frosty white clouds, your heart in your eyes and snowflakes in your hair. I will remember that single perfect moment in my life, that moment I knew I had everything I ever wanted, and whatever happens next, I will die content.
What he says is simply, "Marry me."