After reading this blog post, I would like to add another relationship advice, because I totally agree with the author:
Have fun together, especially go on holidays together.
From personal experience, there is nothing better you can do. Even if it is only a budget extended weekend trip on your bikes (like the one I am planning for Easter). Besides the trip being fun, there is the planning a project together beforehand and the memories afterwards. Even if the weather is shit. You will still have the memories of that one weekend you spent in your hotel room.