Relations between people are so intricate, and it is natural that sometimes they fade and sometimes gain the second wind. Though, this new breath doesn't appear in itself. The best way to cheer up your relations is to make surprises, because they cause a lot of positive emotions.

My simple idea is to make surprises every day.
I offer guys and girls to present small gifts to each other. They can be cheap, but priceless in meaning. For example, guys can make a lot of hearts of paper, write different compliments on them, or just warm words, or the words of love. Then take each day one heart and put it near her door (if you live together, then stick them to the mirror or put at the place, where she can easily find it). She will certainly like such surprises and she'll be waiting for the next morning to see the other note from the beloved person.

Hope you'll like the idea and fulfill it!