Thank you for the response, please don't be concerned about being lengthy, as I always say, the more info you give me, the better I can help.
Let me preface this by saying that 10 years is a very long time to be with someone, and it's not uncommon for us to lose the 'magic' and passion in that amount of time. If you have not talked to her about how you feel, them you are not being fair to her, because she at least deserves a chance to make things right. Keep in mind that any relationship you get into may feel this exact same way after 10 years if you don't learn to communicate and keep things 'fresh'. It takes two people to keep a relationship feeling 'fresh' and new.
If you are telling me that there is no way, no how that anything could ever change how you feel, then there is nothing really that you can do because no matter what you do or how you say it, she is going to be hurt. There's no pretty way to say it nor any presentation that could make it more palatable. The best thing is, if you have absolutely made up your mind to leave, is to be as frank as possible, and don't play games about it. Don't drag your feet and make it more miserable for her, make your decision and act on it.
Think about a few things for me. When is the last time you kissed your woman for an hour? Why has it been so long? Why has the touching (appropriate or otherwise) stopped? Where did the love go? Is she the only one responsible for its loss?
Can you think about those things and get back to me?