Could be a man who thinks he has to buy a "big" present or it isn't good enough/worth it to him? Did you get him a card and/or present? What did he say to that? My husband and I didn't exchange anything but we did go out to eat together. Did he at least offer you a beer?! :-) My husband would have tried to be cute like that if he'd forgotten or messed up.

I don't think any "excuse" is a good one. Explanation, yes (I forgot, I didn't feel like it, whatever) but not an excuse. It can't be someone or something else's "fault" besides one's own.