I've luckily broken down my GF's defenses about the church a little bit. I am dating a great guy who happens to be a very brilliant doctor going into residency very soon. I'm in the exact same pulling-out-my-hair situation that you are. So it is going to be over anyway.
However, be careful to not ask something that may offend your date. God works by small and simple means to bring about His great and eternal purposes. He will not be permitted to bless the child in front of the ward, for instance, so you will have to choose to forego that ritual or find someone else to stand in for the father, which he may not be comfortable with. His dad and siblings are also doctors, hence his mom is quite use to the idea of being alone and independent. I appreciate knowing all you have mentioned since it gives me a bit of insight and some real good tips.
My current atheism bothers him a little but as long as we respect each other it's fine. You just have to decide if the payoff is worth it. I say, Follow your heart. He was my first boyfirend and is an amazing husband. It is difficult to learn to have no expectations towards him, even though our mindset towards medicine is the same. You are a good person and she can see that. Of course she won't want to watch something that in her mind attacks her religion. If you can love them unconditionally with how they are now, then I say go for it. Posts from people who have your same problem occur on a regular basis here on RFM.
On the plus side though, after you leave the church, you'll get to spend the remainder of your days bashing it on Reddit. I've been doing it wrong. He gave me a very clear answer that this was right. Word to the wise, wait a day or two. I have missed anniversary dinners, birthday parties l, Christmas mornings as well as day to day. And unless they are total cretins your ward members will love him too. I really like this girl but, is Mormonism so toxic that I should just sever the relationship before it gets serious. But what does it really mean to be a patriarch, to lead your tribe.