When seemingly good friendships end abruptly!

The theme of the day seems to be ending friendships, and as it were, I have my own tale to tell.
Well, I am sure I have several, but this one is still pretty fresh.

When I was pretty young, 8 or 9 I think, I had a best friend.
We had a lot in common and spent an inordinate amount of time together as best girlfriends do.
This friendship lasted until 7th grade, until there was a fight and then we didn't talk.
I can't remember what the fight was about, probably some moronic prepubescent girl BS.
We made a feeble attempt at being friends again in high school, but even then the friendship was tenuous and awkward (maybe some residual hurt feelings over the aforementioned fight?)
There was always a gap between my social circles - for some reason, I never really "fit in". I always said that my high school stereotype was that I was invisible. I wasn't a jock, or a cheerleader, I wasn't a nerd or a weirdo. I wasn't a burner (even though I ran with that crowd for awhile). I wasn't unpopular, but I wasn't popular either.
I dated a guy my senior year of high school who had graduated the year before, who was popular but only because a cool kid took him under his wing and kept everyone else from picking on him. However, the cool kid could only protect Mark when the cool kid was around.
Even though I was a nobody, my friends told me that dating him was social suicide (like joining the Mathletes)
I don't know what that little anecdote was supposed to reveal, that even in my invisible state, I was still too good to date the most popular un-popular guy?
Anyways, I digress.
This girl was smart. Like Mathlete smart, Dean's List smart, visiting colleges smart.
I was not.
So, the gap widened until I ended up running with the burner crowd. And to be honest, they may have been baked all the time, but they never talked about me behind my back, or made me feel like a loser, like Smart girl's did.
Smart girl went on to graduate, and do things in life that I was oblivious to.

Several years ago, my sister moved into a new subdivision and my nephew made friends with some kids, who turned out to be cousins of Smart girl. Smart girl's aunt was a valuable instrument in reuniting us.
It started out as emails, coffee and the occasional dinner. You know, to catch up.
And things were good. Neither of us needy for attention, and appreciating the fact that we were only an email away.
Over time, my life changed significantly. Sometimes for the worst, but ultimately for the best.
Now, I can only relay my side of the story here, you'll find out why later.
When we first started talking again, I had just split from my ex-husband and was in a serious relationship with someone new, after about 2 years that relationship ended in disappointment, but that which doesn't kill us only makes us stronger.
Smart girl was really there for me and it was greatly appreciated to have a friend who was single and child-less and able to grab a beer with me on short notice.
We both embarked on internet dating (a first for her, I was a veteran by this time.)
I had some luck, and I had some horror stories, and then I hit pay dirt.
I met the man who would become my husband.
Smart girl never got into the internet dating groove. I tried to play matchmaker, but I suck at it and really don't know very many guys worth referring her to.
I really felt a change in our friendship when I introduced her to a guy friend of mine who was recently single.
He's a great guy and I am still friends with him - but his response to "What do you think about Smart girl?" really set the pace for the year to come.
"She's nice, but she's really not my type."
They never exchanged numbers, so guess who had to tell her? If you guessed that it was me, you're right.
She was very, very upset. I felt awful.
Then she said something that really struck me and I still don't know how it was meant.
"How come you have all these relationships and I can't even get 1 date?"
That may not be verbatim, but it's close.
What the hell is that supposed to mean? Do I not deserve to be happy? Am I too lucky? Am I not worthy of meeting someone and having a relationship?
Wait. Let's back up. Let me define "ALL THESE RELATIONSHIPS":
From age 19-25, I was dating, then married to my first husband.
From age 26-28, I was dating one person
At 29, I met my husband. (the relationship continues, unabated.)
Since when is 3 a lot?
I guess when I compare it to Smart girl, it is a lot. I don't mean to boast.
She could have had a crappy first marriage and a humbling break up experience under her belt by now.
I think she should consider herself lucky.
My now husband and I announced our engagement and while I was bursting with love and joy and all that, I still felt like I had to subdue my excitement around her. She made me feel guilty for being happy.
I asked Smart girl to be a maid of honor and she accepted. Briefly.
A month after she had agreed, I sent an email advising that dress shopping was imminent and got a long email reply explaining all the reasons she had to back out.
I was pissed. Then, I thought about it and got over it and all seemed OK.
Throughout this time, I was still emailing and inviting her to gatherings large and small, all of which she said she would come and never did.
These "Unappearances" were always followed by an email or text about how bad she felt that she didn't go.
I still kept inviting her out. I invited her out with friends, I invited her to coffee for just us, I invited her out with my then fiance.
All declines.
When I sent out our wedding invitations, I never got her response card.
When I asked her about it, she said she might have a date and was waiting for him to let her know if he would be her "Plus 1".
The response never came.
Now, our wedding was not formal at all. If she sent the reply card back with just herself, and came with a guest it wouldn't have been a problem and she knew this (I think)
Well, she came to the wedding with her mom, who is a great woman and I was glad to see their smiling faces at the ceremony.
After we were married, we went offsite for pictures and when we returned their smiling faces were gone.
I was upset, but didn't let it ruin our special day.
After that, I still invited her out. Now, instead of declining, she would just send a text 10 minutes before we were supposed to meet and say something came up and she couldn't go.
I continued to text and email, and after awhile, she just stopped responding.
The only way I had to know what was happening in her life was to lurk her Facebook page and I got tired of that.
I tried casually posting on her status updates and she still didn't respond.
I was afraid I had done something heinous to upset her, but after racking my brain I came up with nothing.
Since Smart girl and I are both non-confrontational, there was never a blow up or even a nasty letter.
And because I was afraid that I may have done something to hurt her feelings, I never sent that "What the F?" email asking what was going on.
So, after months and months, I decided that if I didn't hear anything from her in reply to a Facebook post on her wall I was going to unfriend her.
And I did, I started 2010 with one less friend and I have no idea why.
Like I said, this is my side of the story. I don't know what caused her to stop talking to me and I truly hope that it wasn't that I did or said something to hurt her feelings.