You're both at university and you rarely get a chance to slip away and be together? Are you kidding? If you think your time is under attack now, you're in for a nasty shock next year when you enter the workforce!
Seriously - the two of you need to rethink your agendas. I do know how crazily busy life can get in the year you sit your finals, but I also know there are many optional demands on your time too - demands that are unrelated to lectures, tutorials and dissertations. Demands that you're free to ignore! Parties, balls, hobbies, parties, clubs, shows, parties. And yes, these probably do all feel important (not to mention exciting) and they do all contribute to your overall experience of university life, but if you find yourself signing up for everything, it's inevitable that your relationship will pay the price. If your romantic relationship truly matters to you, I suggest you reconsider your priorities. But in truth, I have a sneaking suspicion that what you really need to examine is the relevance of this relationship to your life.
Passion is not something you can acquire from a manual (though technique, to an extent, is). It needs to well up from inside you. You need to WANT this man - the sauciness you're seeking should stem from this desire. If you can't think of ways to liven up your sex life and you can't bring yourself to find the time to dedicate yourself to this man, then perhaps the partnership has run its course. Maybe a fresh start is something you should consider in the months ahead, as you prepare to enter the next exciting and time...squeezing phase of life.