I don't know if you ever quite get past the embarrassment of this fetish, since it is widely regarded as strange by the majority of the world. I think the closest I ever came was my last GF. She didn't care if I wore them, even encouraged me to sleep in them since I had a couple of accidents in bed. She even told me I had a cute butt (I was wearing cloth with plastic pants that had prints)
We would even powder and diaper each other on the weekends when disposables were involved, and many times she would wet hers beyond capacity. Unfortunately, she also had a horrible temper sometimes when we had drinks, I never knew who I was going to get after she had her 1st one, the loving nurturing woman she could be, or the angry venom spewing person that had some deep rooted anger issues. In the end I decided that, as much fun as we had, I wasn't what she really wanted and left.
I'm in a good relationship now, although she does not participate in any way, she is aware of my fetish, has even taken the time to become knowledgeable about what all it entails. She's made it clear that she always wants to see me as a man, and I respect that. I could never imagine placing or even seeing her in a diaper, I just don't see her that way, she is my lover and best friend. I do practice my fetish in private with her knowing what I'm doing, and I don't think I could ever feel completely comfortable wearing one while I'm around her.
Of course I wish I could, that it is no big deal, but as long as I feel it is, it won't happen. We have plenty of other things in common, I may not get my fetish needs met by her, nor will I ever go outside the relationship to have that done. It's clear hat we both need each other, and we have many other needs that ARE met, and for the most part I am satisfied, but still a little embarrassing...