About Valentine's day.... are you in Japan? then I understand what you are going to do, but if you' are in outside of Japan, your action may not be understood/appreciated.
In north America, Valentine's day (with " 's ") is the day to celebrate the LOVE you share with your loved one, mostly with your partner (not even your mom, dad nor children!).
But I understand if you still want to do it. If that's the case, I recommend you to explain what we do in Japan first, then people can understand/appreciate it.
sorry if I couldn't explain it well, I didn't mean that they would MISunderstand you("誤解"), but they just won't UNDERSTAND("理解") why you do that... because my friends and parents-in-law didn't!!
Mlover さん
仮定形は仮定形のままで、今後あるイベントでも、「行ったのに」という言い方なら、I woud have gone (to xx) with him という言い方をすると思います。I would go with him. と言ったら、「行くわよー」みたいな、行ける気満々で仮定形にならないと。後、would have → woulda は口語と言う感じじゃないでしょうかね。人や環境にもよるとは思いますが、would have は wouldav とくっ付いて聞こえるか、would've と発音してる人の方が、まぁ大人になると多いと思います。Would of と書く人もいますけど。余談ですが、似たようなのでkindaとかsortaとか、ofがaになってくっ付いてるのもあります。この場合、a kind of 〜, a sort of 〜 とは使い方が違うので注意ですが。