This is part of what I'm most concerned about, that she may be giving her all and it's not enough for me.
You mentioned hand/oral, she's never ever brought me to climax this way. She's read through the threads here on oral sex, and she's incorporated many of those techniques it's just at the end the whole thing comes across as mechanical not sexy. I often times loose an erection when she tries to do either of those things. I talk to her about what I'd like to see changed, but again everything is just so mechanical with her. I don't know how to address that, and personally I fear that it IS because she's just purely asexual.
The vast majority of the time we do have intercourse I have to finish myself off, and that often times takes an additional 5-15 minutes. It just feels like vaginally enhanced masturbation.
I know I'm talking out of frustration here, but I'm afraid there are some other changes going on within me now. I'm fearful that part of me is just shutting down with her. This has never happened.
For the first time ever, last night I actually lost an erection during sex. I know people say that it happens, but I'm very concerned... because it's coupled with me just loosing interest in her (another first).
Over the past few weeks it's actually taking me a while to achieve an erection during foreplay (also a first).
Additionally over the past few weeks I've just lost interest in masturbating alone... just sick of it, because it represents more failure in our sex life.
I fear I'm loosing interest in her sexually and not sure how to get it back. As of just a few weeks ago I couldn't touch her enough. Now I'm getting to the point where I just don't even feel like hugging, even when she initiates a hug. I've never been that way across all 15 years of our marriage... not once.
I know all of this is unrelated to determining if she is asexual or not... or if I should even try and get a diagnosis. Frankly though I fear that I'm just somehow withdrawing from her. This really concerns me. Part of me just feels some urgency to get answers.
Last night my wife and I were talking, and we realized that when we said that she had a drive 4-6x/year... it wasn't really a drive. It was more like she was open to sex that often... that she was more easily aroused. I fear that she actually has zero sex drive. What's more, is that the 4-6x was related to her 2-3 ovulations, which are soon to be a thing of the past. Those times were better and more exciting for us both, but they are just about gone now.
I want to continue to be patient, and frankly I have no choice... but it's becoming increasingly difficult as of late.
I still have a sex drive... I just feel my motivation to do anything about it weakening... because it just all feels like yet another admission that my sex life is a huge disappointment. I'll go over all this with my ST today when we meet.