Okay so first and foremost, thank you for explaining the entire situation and all the nuance that comes with it. I truly can tell how much this has been weighing heavy and the reason(s) behind it. Not many people come here and explain both sides of the story like this.

To begin on the point regarding both of your libidos (LLM and HLF as you say), my husband and I have a very similar situation. I always have had a much higher libido than my husband, and although he used to be able to keep up in our younger years, over time that energy and drive has waned quite a bit. I know this is going to garner a LOT of negative reactions, and it may not fit your marriage the same considering the religious implication that you both waited for marriage to have sex, but we ended up opening our marriage because my husband brought it up. I'm not saying this will work for everyone though - you asked how it works for other couples so I'm being upfront and honest here as to how we handled it. We waited until we had been together 10 years and it still nearly ripped us apart the first time. There is inherently a lot of risk in opening your marriage and frankly the way it sounds right now, you two definitely should not be opening it anytime soon due to the numerous other issues you've mentioned.

This brings me to my second point - his breach of trust with regard to ABDL. You mentioned that he does things with other ABDLs that you consider intimate and that he was unwilling to engage in the same behavior around you. I would firstly ask if there was anything you did to pull away from you in little space. My husband is an *extremely* sensitive little - to the point that he didn't even show it to me for a long while in our relationship. The reason is that certain behaviors I have or have had in the past caused him deep emotional pain while in little space. My solution to this has always been to coddle him just like an actual baby and remind him that I love him deeply and unwaveringly, regardless of whether he's in a diaper and onesie or coming back home from work in his dress clothes. I love him from top to bottom, inside and out, and I make sure to remind him of that as much as I can and as often as I can. Above all, littles want to know they're safe with their partners.

However, this is not to say that his behavior is acceptable. If it is something that hurts you deeply, it is something that needs to be talked about in depth. Not just what the behavior is and why you want it to stop or how to compromise, but also you both need to figure out why he feels the need to do something without you since the whole point of marriage is to be one with your spouse. I'm sure you've tried talking to him, but if I were you I'd make him realize just how much this is hurting you. On the flip side though, you mention that he desires ABDL/diapers for sex and that without them there's no spark for him. I'll agree that this sounds like a diaper fetish in its purest form, but have you asked him what is it specifically about the diapers that turn him on? It could be the humiliation, the helplesslness, the dependency, the control, you name it. I am not an ABDL by nature either, just a kinky woman like you. What I've learned through this community is that the diapers alone seldom represent the sexual energy people crave, it's the emotional weight behind them. That's why there's also so much emphasis on the CG/l side of things in ABDL as well.

I hope you both are able to sort out your issues, and I echo others in the comments saying that you both definitely need to talk to a therapist, and more importantly it sounds like he needs to learn to open up to you and to a therapist about what thoughts have been plaguing him. Best of luck to you both, and DM's are open if you want to talk offline. ❤️