Always feel a bit awkward wishing people a happy anniversary as it seems like such a personal day for the couple involved! (I don't even wish my parents a happy anniversary!) But I hope Nic and Alice had a really special day filled with love and light!
Yes, you always have to be careful with congratulations, don't you?! The happy anniversary couple might be having a fight right then, or the birthday wishes might be to someone who wishes they were getting younger, not older, lol!