Maybe she is not that in to you. I think if it is possible to talk openly and honestly, you should let her know how you feel and encourage her to talk sincerely about her feelings. Sometimes to be really happy in life, we need to move on. Sorry if this seems like an opposite to what you want to hear but I have been there. I was not happy with my 1st marriage for many little issues that were never really resolved because they were never discussed. I became distanced and sex became a horrible task! I simply fell out of love.