Tiggs2 I hope you don't mind, but I found your post a bit hard to read, so I broke it down a bit and re-post below in case it's easier for others to read to and help with replies.
FWIW, I think your friend is distancing herself from you. It may be conscious or only semi-conscious at best but she's finding herself a new friendship group and they are absorbing her attentions and energy.
Your friend may well not wish to "cut the thread" with you actively and might even deny that's what she is doing if you ask, but in practice cutting the thread is the outcome of her behaviour.
And I doubt that you can change her. You could try pointing out to her that the only time you hear from her is when she wants something and leave the ball in her court to see if she gets in touch and tries to keep the friendship going...but to be honest I'm not sure what else you can do.
It is sad and it's a friendship that has been important to you and her for years but it may be changing now.
OP POST
I've always known and been friendly with a lot of people during my life but only ever had a couple of close friendships.
My OH is my best friend and has been for many years, but I do have two female pals who I have known for 20 years. They are both very different in character and personality, and I admit I was much closer to one of them, well until recently anyway.
We only ever used to spend the odd afternoon together but always sent regular texts, had long phone chats and generally knew what was happening in each others lives. That all seemed to change last year when the texts and promised calls got further apart, and it was always the same excuse of "sorry been really busy", but I thought to myself, not too busy that you hadn't visited Facebook that day!
There seemed to be a couple of new friends on the scene who appear a bit "rough", not like the type of people she has been friends with before, really bad language used on FB, along with fall outs with people etc. I'm not saying that we are snobs, not by a long chalk, but I'm surprised really. I got so far behind with what was going on in her life that I was starting to think that she couldn't really be bothered telling me anymore, it even it took her about three or four days to reply to my texts.
In return she didn't know when things had happened in my life, and did not seem really bothered anyway. Saying this though when members of her family have been unwell, Ive sent regular messages to ask how things are, but the same doesn't apply to me or mine. I was worried about my OH for a time but no message or calls offering support.
I have even offered to call in for a cuppa but have been told its not a good time! My friend has let me down a couple of times aswell in the past, but ive just let it pass, So though we remain close friends to date, I get annoyed when I get a text out of the blue asking for a favour! The messages come across as how are you etc, but there is usually something I am needed for at the end.
I asked a very, very, small favour last week, have also asked three times prior, but so far I havent had a reply from her as she obviously couldn't be arsed, so I am sat here now wondering what the excuse is now.
I know that she will leave it as long as possible, then text me when she thinks ive forgotten about it. It makes me angry because me and my OH went to hers two weeks ago as she needed something doing!
I think the most hurtful thing to date was my Birthday, Ive always had a card and small gift, but this time a card never came for me and as I was going away on a break then, I got a text to say we will go out when you get back and you can have your card then, even though it would then be 9 days past my Birthday, no apology, nothing.
My OH never got a card either this time, and though its not that important, I have always had them off her in the past. About 10 months ago a person we both knew died suddenly, and with all the upset my friend said that "both" of us should make an effort to spend more together as life is too short! I then suggested meeting up once every four weeks or so for lunch/shopping but was told "yeah but I don't go shopping much now and also I'm saving for a holiday".
I just feel hurt and a bit let down by all this as she has always been my closest friend and if we do get on the phone, we tend to chat for ages like nothings happened, though this rarely happenes now. Can I ask for your opinions please and what would you do?