Azure, I started reading your thread with an open mind. I think there are things one can do to generate more of a loved-up feeling in a partnership that's gone stale. I even think it can be worth doing this when only one partner has lost the feeling. But, I'm sad to say, reading your thread has made me dislike your husband. I feel you'll be a happier, more fulfilled and generally more enchanting individual when you are single.
The first red flag was where you said you're realising it's possible to have fun, thanks to your hobbies and renewed friendships. If you only realised that fun is possible outside your marriage, then that marriage has not only been joyless for you but has closed your mind to the very possibility of joy. This is no good. In 23 years, a good marriage would have been at least 30% fun. Hell, my parents had a godawful war of a marriage but even theirs was about 25% fun!
I'm deeply unimpressed by an inconvenient weekend away, in which you had to prioritise economy over comfort. That wasn't a treat; it was an imposition. If this is as good as his romantic gestures get, he's in no position to lecture you on relationship building. In fact, the whole lecturing thing is extremely offputting. Why should you be doing all the running, making all the effort? His efforts seem rather feeble at best.
His behaviour when you had pneumonia was unforgivable. I can only imagine how ghastly it must have been for you, to feel so poorly and to realise your partner had given you up for dead, yet still couldn't be bothered to come and comfort you! One of the primary reasons for forming a long-term commitment is to have support when things are bad. When your partner cannot face supporting you, he fails you and, in a meaningful sense, nullifies the commitment. A partner who's done this has no right to demand continued commitment.
I think his demands on you are founded in a recognition that you actually deserve better than him. He's trying to tie you to him by guilt, fear and obligation. This won't work long-term and is bad for you now. I also don't like what it's teaching your children.
You don't need permission to end a marriage.