Don't question too much the good days. You will surely have a lot of ups and downs, so when you aren't down, just roll with it.
I agree, wouldn't read too much into her calling you today. She probably has guilt about what she is doing, after all you were together a long time and she does have feelings for you (even if she isn't really sure about them right now). But it is nice that she did that, she is not totally cold, and maybe she would like to remain friends. You had to become friends before you got married, and you will likely have to rebuild that now if there is going to be a reconciliation, so work on being friends if you can, and if she will let you.
Re: your second thought: I agree, it seems that the WAW moves so very quickly, she thinks that now she's made up her mind she has to change everything as fast as possible. Maybe it is to avoid their doubts, maybe it is cause they think the faster they get rid of the old life the faster they can be happy. Perhaps that is true sometimes, but I think usually they will come to see that it wasn't just the LBS that made them unhappy, that they will need to work on themselves a bit too. That's why letting go and detaching can be so important--not just for you, but to give her an opportunity to see what is going on and look inside themselves a bit. Maybe she will, maybe she won't, but she never will if not given the chance.
Me: 43 W: 41 Together 2009, Married 2011 Sons 10 and 6, Daughter 5 Bomb 2/21/21. W moved out 10/2021