I can't think of any secret formula
many things
here's a few that maybe count for something
tell her you love her, every day
buy flowers for her, not for a special occasion, just so you can tell her you love her
make her laugh, laughter is an amazing tonic for the soul
hold her close in the sad times, don't be scared to cry with her
Do things together, go with her to the ballet, you might even enjoy it
we have traveled extensively together, over many years
experiencing good times that are forever in our memories
but also some scary, life changing moments that make you stronger together
we also chose not to have any children
no secrets, tell her everything