Can A Long-distance Relationship Last For 4/5 Years???

Hi I need some advice.
The Guy my older sister loves will just be coming back from his University….by the time she is only just LEAVING college to start her University. How can they stay together? Do long-distance relationships work? If so….can they work for FOUR YEARS (or more!!!!!) What is involved in a long-distance relationship? How do the two people keep the relationship going? PLEASE can anyone out there offer me any advice via email??PLEASE HELP!!!!!!!!!!!!!!!!!!can you offer me any advice as my sister seems very upset and I don’t know how to help her.
Can a long-distance relationship last for 4/5/6 years..OR MORE??
could a long-distance relationship of the one I’ve just mentioned above actually work??