Hello - I registered to reply to you! You need to be re-assured that men being at births is a very, very modern trend. In fact for thousands of years men were keenly kept away from births.
Here is an interesting article you may find helpful:
http://www.wombecology.com/masculinisation.html" onclick="window.open(this.href);return false;
My husband was with me throughout most of the labour for son No.1 but waited outside during the pushing bit. His sister was my fabulous birthing partner and far better than he could have been at that time. He was my partner for birth No. 2 and was lovely, and I'm very glad he was there, but I might have benefited from a softer, more gentle and feminine approach to support!!!
I wish I'd known all this before my first birth, because like you I felt short-changed that he wouldn't be with me like 'normal men'. Well, it turns out it's far more normal historically; and long-term-historically, like throughout our history! - for men to be kept away. I'm all for progress but when there are good reasons for our bodies to look back then it's worth doing.
The birth, as you say, is momentous - but there is so much surrounding it that is momentous too and he'll find other ways to be involved where he can.
Good luck.
x