Hi, OP, I've namechanged for your thread. I really feel for you, as my partner is similar. He lacks initiative and assertiveness, and will go to some lengths to avoid confrontation. This has led to all sorts of conflict in our relationship (ironically), as I learned early on that if anything difficult had to be dealt with it was going to have to be me who did it. Not just that, which is bad enough, but because he avoids confrontation, everyone thinks he's Mr Nice Guy (and I'm the difficult old cow by contrast), which means that no one has ever understood my frustrations with him. I feel that he's not prepared to piss off anyone except me - which is all the wrong way round really. It has been really bad for my mental health, because whereas he sails along avoiding anything unpleasant, I get to do all the fretting and managing of difficult situations, and put up with all the stress. Basically he contracts out not only his difficult tasks to me, but also his difficult feelings, which takes its toll. He didn't specifically let me down in the context of our DCs' births, but I did have a difficult birth with one of them, so I do also understand the fallout from that kind of experience, and how hard it is to process, when as a culture there is so much emphasis on 'you had a live birth and that's all that matters'. It's hard to argue with that, but it doesn't in itself take away the sense of trauma, and the loss of the experience (and therefore child) you expected, and it's hard to explain that without sounding loopy or as though you have your priorities all wrong.
I have given up expecting my partner to take responsibility for certain kinds of work within the relationship. While our children have been small, I've assumed responsibility for things I know he won't, and focused on the qualities he does bring to the table - for instance, he is very caring and hardworking, and we have similar values and views about life. However, what I do think is that these things don't really go away. I think unassertiveness and lack of initiative has its origins in someone's relationship with their parents and family of origin, and is about fear of the consequences if a person diverges from the dominant worldview of the parent - either not being allowed to diverge (and resenting that), or fearing not being allowed back into the fold if one diverges (and so fear of rejection). I think that that leaves a person with a lot of unresolved issues that play out in subtle ways in their closest relationships. So in a way, I think that lack of assertiveness is the tip of an iceberg that has the power to totally fuck up relationships in all kinds of unforeseen ways. I could give you some examples from my own life, but they wouldn't necessarily be pertinent to you and your marriage. Suffice to say there's a lot of anger and resentment, much of which is misdirected, and I often feel like I've been cast in the role of parent.
My advice is not to assume that this will go away or fix itself, or doesn't matter in the scheme of things. I think you should have counselling to get over the trauma of a bad birth experience, and this will probably help you cope with the ways in which your DH has let you down on this occasion, but it won't change the unhealthy interpersonal dynamics he's bringing to your relationship. I actually think he could do with some long-term psychotherapy to get to the root of the problem, but if he refuses or it can't be afforded, that doesn't stop you reading around the subject, talking it through with him and trying to understand why he is the way he is. My partner and I are probably heading for the rocks now that the kids are older, as the amount of water under the bridge means that even if he did address his baggage now, he's killed a lot of the feelings between us in a way that can't be undone. So maybe don't be me if you don't have to. 