Seasons of Friendship

Does anyone else seem to go through seasons with their friendships? Since high school, I've always seemed to have lots of people around me. Mostly good acquaintances that I would call "friends." People that would congregate in groups, but few that I ever got together with individually.
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This continued when I moved to Phoenix after college. My best friends were 6 girls that I met with weekly for a Bible study, yet I only ever hung out with 1-2 one-on-one. Maybe that's just me...
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Once I got married (and most of my friends were still single), Mike and I found some "couple friends." And throughout our marriage, we go through phases of hanging out with the same couple A LOT for a few months, then we'll either spend the next few months with a different couple or go through a phase of spending lots of time just the two of us. Or more recently, as a family.
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Regardless of how often I see someone, I'm one that holds on to friendships. My Christmas card list is out of control and it wasn't until last year that I finally started deleting addresses from my files, due to years and years of not getting Christmas cards in return. I try to keep in touch with people across the country and across town, even though our lives may head in different directions.
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One such friendship has taken an interesting turn. Let's call this friend, "Dana." I met Dana at the wedding of a mutual friend. At the reception, somehow her past boyfriend came up in conversation and I realized that I'd been praying for her the year before. I knew her ex-boyfriend, but I didn't know her. And at the time, he was abusing her and she was stuck in the relationship and our friend who was getting married had confided in me about the situation. This may or may not have been the reason we clicked so quickly, but regardless, we clicked.
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Dana soon got married and we both got pregnant around the same time. We kept in touch, but grew even closer when our babies were born a day apart. She was one of my first all-natural, home-birthing, home-schooling, non-vaccinating, no preservatives, sugar-free, goes-against-the-grain-of-society friends. I learned a lot from her and wished we lived closer.
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Here we are 6 years and soon 6 kids (between us) later. Once she had her 3rd, life obviously got a little more complicated for her. When I had to reschedule our recent play date (our first in almost a year) a few weeks ago, her response caught me off guard. She said, "No worries! We can just be email friends." HA! I think not. That's not how I roll.
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I've run into Dana a few times at church lately and realized this weekend that she's quite serious. There are no hard feelings, but she's come to a place where she knows that we live across town from each other, have our own little network of friends, each have three young kids 5 and under at home and that get togethers are unlikely.
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How sad is that? I've never had someone verbalize the inevitable. I've drifted away from friendships and I've grown apart from people over time, but never before have I been in a situation where it's been laid out so honestly.
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Maybe I'm naive to think that it's possible to have friends all over town that run in different circles as me. Maybe I need to concentrate on and appreciate the people I know and have met that have kids my kids' ages, go to their schools and live in our neighborhood. Maybe I need to simplify a little.
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Or maybe this is just a rare, one-time occurrence.
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Disclaimer: there are several of you reading this post that are the exact type of friend I just mentioned. Please don't think I'm ready to dismiss our friendship! This whole situation just has me pondering and you know me...I have to get it out of my head. Much love to all of my friends - especially "Dana," if you're reading this!