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I went through a similar time with a friend on mine during university... we pretty much stopped hanging out since frankly we were in pretty different places.
Mary sounds like right now she wants to be the center of attention, and do a lot of activities that the LW has no interest in. See it from her point of view as well though -- the friend she used to do a lot of stuff with is now in a committed relationship, and isn't into going out and "picking up" as she used to be. That's a loss for Mary. She sounds like she's gone further down a path that the LW decided to fork off from.
I'm not excusing her behaviour, just saying that as she has changed from the "college days" so has the LW.
The thing is, sometimes as time passes our paths come back together. Maybe Mary will get married and settle down. Maybe she'll have kids around the same age as the LW, and no longer want to hang with 35 people and spend lots of money on stuff. Or maybe the LW will break up with her partner, and decide that she's bored and sick of the hiking and musem-going life, and ready to join Mary back at the party.
You can let a friendship slide a bit without abandoning it all together. Things might change, or maybe they won't. Time will tell.