BigD, have you tried chatting online? MSN Messenger, for example, lets you chat in real time and it's much better for lessening the tension of voice-to-voice emotional reactions that come with the phone. Or, if you want free phone, again with MSN you just need a microphone/headset (pretty cheap, really) and you can talk basically like you're on a phone, even over the Atlantic. You can also get a webcam that helps you see each other when you are chatting... and believe me, with long-distance relationships, having that daily visual/audio connection is almost crucial. Sometimes it can make things harder (wanting to have the physical aspect but knowing it's impossible), but I think the pros outweigh the cons. Do you guys write each other letters? Do you do little things for her to maintain that in-loveness? It's really important to cultivate the atmosphere of your relationship (including seemingly meaningless romantic gestures, which are actually VERY important), otherwise communication breaks down and you end up where you're at.
By the way, in general, people get really insecure and sensitive over long distances and time separating them. (see my thread:
http://www.tfproject.org/tfp/showthread.php?t=84430 ) I guarantee you will see how common it is, esp. with women. We just read so much into everything, especially since guys seem to disconnect with us emotionally when we are out of their sight. I'm telling you, the more distance you have with her, the more attention you need to pay her... and if you aren't as into her now, I'd say be honest with yourself and tell her you don't have the energy to pay as much attention anymore, which basically means you go back to being "friends" (whatever that means). And it's vice versa too, she should be very willing to pay attention to you... etc.
And Kramus, maybe this should be another thread or PM, but I'm curious as to what the "differences" are that you spoke about. You were married for 24+ years, and what happened? Where were all the differences during that time?... I mean, did they come to light after time, or were you both just so busy with family/jobs etc that you didn't notice? This is the kind of story that kind of freaks me out about marriage, so that's why I'm curious.