I recently finished reading The Five Love Languages by Gary Chapman (thanks to Kimmy for the recommendation). It's targeted at married couples, but the concepts in it are interesting and useful for any close relationships -- boy/girlfriends, family, friends -- as well as for just understanding a little better how people in general tend to interact.
An early section of the book makes the point that the "being in love" experience (or "limerance" -- did you know there was a word for it?) should not properly be called "real" love at all. Sounds a bit depressing, but that's not to say that it isn't a wonderful thing all on its own, and the author frames this point in such a way as to make it very clear how to develop this stage into real love. And of course, the rest of the book is about the tools for doing just that.
Chapman describes how people express love to each other in terms of five different languages: Words of Affirmation, Quality Time, Gifts, Acts of Service and Physical Touch. We each tend to be most fluent in one of these languages, and if there is a significant difference between partners then it's really easy to get into hot water. Each person could be trying to communicate their love to the other but just not be getting through at all. Luckily, the solution to that is also easy: just read this book, figure out your respective primary languages, and start learning to speak them to each other. None of it is inherently difficult, it's just a matter of awareness and choice. For instance, I tend not to do much vacuuming, just because it isn't important enough to me to put out the effort. But it doesn't really take that much effort. If I knew that my spouse's primary love language was Acts of Service, I could easily offer to vacuum the house periodically, as a choice to express love to her. The idea seems so simple, but judging by things like the divorce rate in this country, it may be too simple for a lot of people to notice.
Incidentally, one of the reasons that the limerance stage is so wonderful is that we tend to express love in more, if not all, of these languages, rather than sticking to our primary one. I was also interested to read that this stage tends to last an average of two years, which is plenty of time for a lot of people to run off and get married before they actually figure out how to relate to each other in the long term.
Reading through the book, I was having trouble for a while figuring out what my primary language might be. A lot of them just seemed equally important. There were some interesting tips at the end though, for figuring this out. I'd say I'm primarily a Quality Time person, with Words of Affirmation and Physical Touch following close behind. Gifts and Acts of Service are a bit farther back, since I tend to be content if everyone (including myself) can just take care of themselves in these departments. These latter two are also things that I'm more comfortable giving than receiving. So if we were going to get all Quizilla-like about this, you could call me a QWPGA. But we won't. I'll just stick with recommending this book to anyone in a relationship of any significance at all.