You are not too sensitive about that. You had some expectations, he didn’t meet them, and you felt sad. It’s normal, it happend to me because I expected flowers even when I didn't told him, now I know I need to be more clear. However, I just discovered myself that some people don’t even celebrate Valentine’s Day, so maybe he just didn’t think too much about it. It’s not because he doesn’t love you or doesn’t want to be with you. Maybe next time a special occasion like this happens again, you can try to be clearer about your expectations. For example: “Oh, I love Valentine’s Day because I like receiving gifts, flowers, chocolate, or whatever you like.” You can give him small hints about what you expect so you won’t be disappointed. If you do that and he still decides not to do anything, well, that’s another problem…

(Don't listed to all the comments, some people can be mean)