03/22/2013 07:12 am ET Updated May 21, 2013

FACE IT: Friendships Come In All Shapes

I was talking with my friend Joanne in Los Angeles this week, as she was leaving for her condo in Palm Springs. I asked about the desert social life and she replied, "Well, let's say we have friends there who wouldn't be our friends here." Suzanne told me about the new friend she had just made at a weekend silent retreat. I quickly shot off a few zingers about eye contact and love means never having to say anything. But she was perfectly serious. And then there was Hilary who remarked one night, "I am not taking on any friends over 50 anymore." (She is 65)

All this got me thinking about the numerous varieties of friendships, and how they fit different needs at different times. There are those precious few folks with whom we share history that may go back to grade school. Like our first loves, they bring a sense of comfort, millions of memories (even when the shorter-term one goes) and of course, they see us as we were then.

In truth, these are often people we see only sporadically, and if we just met them now, would likely not be our chosen friends. Keeping up such relationships may not qualify as an "obligation" -- like visiting the cranky relative in the assisted living facility -- but is it friendship in its most complex and complete form?

Likewise, there are professional friendships, which may be fostered by an intense project, hatred of the horrible boss or simply a lifeline in a lifeless job. Once again, the question is, how many of these would or do continue outside the office or when one moves on?

There are the fitness friends, those you shoot hoops, or downward dog, with; the AA buddies who obviously share a true mission, and make for necessary evening companions; the "About the Kid" partners, those we sat beside as our children climbed the jungle gym or swung the bat in Little League. When the game or class ends, when sobriety is the new normal, when the kids move on, up and out, how many of these relationships do we maintain?

For me, the true friendships are those that can sustain long and inconvenient treks -- in Los Angeles, for example, crossing the 405 at rush hour. You may have enjoyed hanging with that couple in New York City, but what happens when they move to Westchester or, God forbid, New Jersey? It means actually picking up the phone rather than emailing when someone is in need of advice or even a hug. (On the flip side, there are those who only step up when a friend is in crisis, to prove they are the best friend you have.)

Other questions on the friendship test might include: Would you tell them if you knew their spouse was cheating? Do you find a way to stay close even when they become involved with a jerk? The answer to the first is probably do unto them as you would want them to do unto you. The answer to the second is you will do a lot of lunches with the old friend who married that narcissist or crashing bore.

Like so many others, I find myself "pruning" my address book as I get older; yes, some because they are no longer with us, but others as I realize they really aren't the people I choose to spend these precious years with. That's when the LTS (life's too short) theory comes into play and I ask: Do they give back? Do they share key interests? Do they agree Lena Dunham is overrated? Do they brag about their children too much?

As we nestle into our empty nests, as we stay in as much as we go out -- choosing who to spend time with is critical. I know what Hilary meant when she said she was not accepting new friends over 50. "My father is 92," she explained, "and he has no one left in his life." Hanging with younger friends is a hedge against loneliness later on. What's in it for them? Hey, it's always nice to be the youngest person in the room.