"I once invited her on a hike and to dinner at my house afterward; she invited five people along without asking me first and then wouldn't let me know whether anyone was coming, even though I called her several times."

The friend INVITED 5 people, but it wasn't clear whether all 5 had actually accepted the dinner invitation -- which is pretty important to know when you're cooking dinner.

So you have two options.

1. Continue friendship entirely on Mary's terms. (You know what these terms are -- you make plans, she shows up whenever the hell she wants, with whomever she wants.)

2. End friendship. (Although it sounds like, from Mary's perspective, the friendship is already over. You're a casual acquaintance, part of her collection, to be included or ignored at her whim.)

Maybe what's killing you is that if you stopped calling or talking to Mary, she might not even notice. And you want her to notice. If you leave, you want her to feel sad about it. You want it to be kind of dramatic. But it won't be. It will, however, be better for you. Maybe someday, Mary will be the kind of friend you want. Right now, she isn't. So cut the cord. Or you've got nothing whatsoever to complain about.

I know it sucks when this happens to you and as a mother it now sucks watching this happen to my teenage son. People change. We change. I think if we stop thinking about things and relationships in "happily ever after" terms we could probably 'flow' along more easily in life, that is accept change more easuily.

I'm nearly 50, and I can tell you that the friends I had in HS are gone, mostly because of distance. But that's not all. In high school, you really don't have a handle on who you are yet and your friendships are often socially expedient. I hung out with a group of girls that weren't upper echelon popular, mostly because none of us were willing to sacrifice our opinions and experiences to the mass mindset necessary for what passes for popularity among the largely unformed. We were art geeks who'd all been well-traveled (except for one - the sole cheerleader in the group who was too shy to be popular).

I now have very little in common with most of these women. One has five children and a husband that doesn't treat her very well. I can't identify. One spent time as a receptionist for an illegal brothel and was a drug mule for her much older boyfriend and ended up in a Columbian prison and is now under house arrest with her aged mother after being extradited (you can't make this shit up). One married and adopted two girls from China. She's not very demonstrative and I always felt like she was making an effort to keep in touch.

But, while I'm still single, my best friend (married with two boys) who I met in my mid-twenties - and is an 18+ hour drive away - has remained my friend because we truly love and respect each other - even though our lives are very different. Like any relationship it takes work. I have to deal with the fact that her husband and children are her main priority and that the "girl stuff" we like to do has to take a backseat for awhile. I did manage to guilt her into a long weekend visit sometime in the Fall. Yay! Toxic friendships do (and should) end.

Real friends are considerate- they show up on time, they keep to their commitments and they can empathize with you. That means they don't dominate your activities, or wrench control from you and your plans. That means they don't leave you in the middle of Crackton and show up 45 minutes late.

Most importantly- true friends can put their own ego and desires aside (at times) for your benefit. True friends realize that sometimes you put the other person first.

I see the pattern of behavior and you see it too. She's not interested in being in any social situation where her worshipful gaggle isn't present. If she were a true friend she would be comfortable being alone with you- hiking, dining or having that heart to heart. That's what true friends are. People who can share group activities with you, and can also share the intimate moments of alone time.

I know what it feels like because I've been there too- treated like a pet dog and following people I thought were friends- but never treated as an equal. It sucks. And the loss of self esteem and self respect is not worth it, even if you've had fun together in the past.

Let it go, mourn it, and meet people with whom you can share mutual respect, and fun times with.

You seem to have had a lot of patience, all the instances you mention are things that would have enraged me; entitlement and lack of consideration are two of my 'hot buttons.' However, in reading this over, I wonder if something else is going on, perhaps some underlying issue has triggered this transformation. Not that it is your responsibility, per se, but this relationship is clearly very important to you.

Before you completely call it a loss or relationship permanently changed, it may be worth asking her in a direct, non confrontational, and supportive way. It coould be her health, a personal issue, something at work, the possibilities are endless. Anyway, just a thought.

So I also have/had a good college friend that I was very close to, spent lots of time with and now I never see. Though in my case, I'm the single childless one, and she's married with two kids. She's the one who cancels plans when we make them, shows up late, and when we do hang out, she's distracted and not really there. She even has her own set of new friends (moms in her 'hood) that she invites along when we hang out.

I think as many writers have pointed out, this is just something that happens to women not just in your 30's and 40's, but through your entire life. It can be any sort of circumstance, but we all make different life choices and grow apart. I definitely went through a sort of mourning period, but I've just accepted that this is how things are now, and I hope that in the future when the kids are older, we'll start hanging out again more.