15 year relationship feels at its end.

I've been with my now wife for 15 years. We met at secondary school (high school) and have been together ever since. She's the only woman I have ever been intermate with and we have shared some great times (birth of my 3 children) and some bad times. The problem I have is that she is never intermate with me anymore, and when she is she just offers herself to me as of she thinks that's all I need. There's no foreplay or anything. We don't talk anymore, every time I'm talking to her she will start talking to one of the kids, or playing with the dog and then she gets mad at me when I get mad at her for not listening. It has been like this for about 11 years and I'm finally seeking some sort of help. I've tried talking to her about this in the past but she just doesn't see it. Nothing changes. I miss her and need some help. I don't want this to end.