Well, the only way you can actually gain height now is by placing lifts in your shoes. Afer a certain age, our bodies just stop growing. There is no magical cure or remedy for you to grow a few inches overnight. Too bad there isn't because I've always wanted to be taller than I am right now. You are lucky to be a man because you have a longer time to grow than women do. Most women stop growing by the age of 16, where men can continue to grow until they are around 20.
So basically if you are only looking at an inch to grow, I'd suggest that you look into some lifts to put in your shoes to give you that extra bit of height you're looking for. Good luck on this one. I really don't see that height should make such a big difference in a relationship if you both care about each other.