So your boyfriend is busy with school, life, etc. and doesn't seem to have much time for you. That doesn't mean it is time to give up, here are tips on staying romantic when time is a premium.
Make use of texting. Text him at night to tell him you are thinking of him. This way dreams of you will fill his night and even though you aren't together physically you will be together mentally.
Text him during work with a sexy message such as wish you were here oh the magic we could make. Make sure it is clean enough that if his colleague saw it he would not get in trouble, but still gets the sexy message across. This way he will be thinking and waiting for the next time he can be with you.
Avoid being a nag and complaining about him not spending enough time with you. Realize that he is focusing on his career and school now so you and he will have a more financially secure future. Although it may be tough to see, realize he is doing this for you so you don't want to seem unappreciative. A little negativity when you rarely see each other in person can sabotage a relationship.
Last but not least make the most of your time together, cuddle, smile, and avoid talking about serious things that could bring you down. You want to focus on just you and him so the time will be magical and he'll do everything he can to maximize it.