Was is something I said?

By the looks of my other postings, I am the one who seems to have a problem with friendships, and all this time, I thought it was other people who had the problem.
When a friendship starts to fade and you try to reclaim it, when do you let go? How hard are you required to fight? When do you give up that fight? Do you step in the ring and give it all you got for the full 10 rounds or do you wave the white flag after only a few bouts?
I guess what is making this one hard to either fight for or let go of, is the fact that nothing has happened. There has been no fight, no argument, not even a nasty phone call. I think what happened is life. We get busy, stuff happens.
I have a friend, who I consider a very good friend. My husband and hers were/are friends, our kids were/are friends. We were close. They moved a short distance away, just over a year and a half ago. At first, we saw each other regularly and talked on the phone often, but then we just slowly drifted apart. We would talk once or twice a month. We would see each other maybe once every other month. About a month ago, we both tried to make a real effort to stay connected. (I guess I tried harder than she did.) As of today, I have sent two emails, called at least 6 times, leaving four messages. I have asked her to let me know what I have done wrong, just so I would know and maybe try and fix it. If she no longer wants to be friends, that is fine with me, but at least give me the respect and respond to one of the messages/phone calls/emails. I think I can handle it.
So now, do I let this slip into the unknown? Or do I try to get an answer?
I just want to know, was it something I said?