DEAR ABBY: I’m in my early 20s and the only one in my circle of friends who is currently in college. They all want to hang out all the time, but most of them live more than 100 miles away. I have a strict school schedule, and I am required to study and earn high grades or I will be let go from my university.

I don’t like feeling like I am being a jerk telling my friends I can’t make it to certain events. How can I explain to them that I can’t drive there every weekend to hang out? Sometimes I wonder if we’re growing apart because they aren’t doing the same things I am doing. Is there something wrong with me because I am still holding on? How can I explain to them that we can’t be as close as we were? If you could help me figure out how to explain my situation without feeling guilty, it would be great. — BUSY IN CANADA

DEAR BUSY: There is nothing wrong with you. Relationships do not always stay static. Most of them ebb and flow as yours are, so please stop flogging yourself for making mature choices.

Being able to prioritize is a skill you should be proud of. You don’t need to make any grand speeches to your old friends about why you see them less often. Just continue explaining that for now your education must take precedence over your social life because if it doesn’t, you may not be able to earn your degree. If your old friends are really friends, they’ll understand.

P.S. Look at the bright side. If you aren’t spending chunks of your weekends driving back to your hometown, you will have more time to develop new friendships at school, some of which may last a lifetime.

DEAR ABBY: May I offer a suggestion to pet owners who hire pet sitters during the holidays? If you are happy with their services, consider giving them a tip.

Every year I am astounded at the number of clients who don’t give me a gratuity on Thanksgiving and Christmas. Many — if not most — tell me how pleased they are with my services, but surprisingly few do anything more than that. I confess, it makes me feel underappreciated.

Often, when I ask friends if they tip their sitters, they say it never occurred to them! So if you have a reliable sitter and you’re happy with his or her work, please give them a little bit extra for working on the holidays when most of us relax and celebrate with our families. — CAT SITTER IN SAN FRANCISCO

DEAR SITTER: Tipping at holiday time can be stressful, and not everyone considers an independent contractor someone to whom they need to give extra money. (Would you be comfortable getting a fruitcake instead?) While I’m pleased to put the word out for you, because you feel you aren’t being properly compensated, perhaps you should consider raising your fees in November and December.

Dear Abby is written by Abigail Van Buren, also known as Jeanne Phillips, and was founded by her mother, Pauline Phillips. Contact Dear Abby at www.DearAbby.com or P.O. Box 69440, Los Angeles, CA 90069.

What teens need to know about sex, drugs, AIDS and getting along with peers and parents is in “What Every Teen Should Know.” Send your name and mailing address, plus check or money order for $7 (U.S. funds) to: Dear Abby, Teen Booklet, P.O. Box 447, Mount Morris, IL 61054-0447. (Shipping and handling are included in the price.)