I've been changed by multiple partners. My 2nd girlfriend and Mommy changed my wet diapers and I had a Mommy friend who changed me quite a few times, wet and messy. My current GF and Mommy has said that she is fine with changing diapers, but as she is long distance, we haven't made good on that yet.
Being changed by someone who understands and accepts this side of you is one of the most beautiful experiences you can imagine. The sense of bonding and emotional intimacy is unlike anything else. In that moment, time slows and you feel like you've actually gone back in time. In that moment, you feel as though the person changing you and taking care of you in that way sees you the same way that you see yourself
Of course, there are other parts of the Baby and Caregiver dynamic that make me feel instantly little and accepted; cuddles, feeding time, bath time, being put down for a nap, etc., but diaper changes rank pretty high as well.
It's always a little nerve-wracking at first and it's quite common to be embarrassed, but when you get use to it and it becomes a part of your dynamic, the sense of acceptance, elation and joy that one gets is nothing short of life-affirming.
I'm sure what one gets out of a diaper change by an S/O will differ based on whether they are an AB or a DL or some midway point between the two, but I genuinely hope that all my padded pals here can experience a diaper change given to them by the one that they love at least once in their lives, it's a really special thing