In our family's budget, we also have a line item for "short term savings." It covers infrequent expenses (like car insurance) as well as maintains our emergency fund. It's good that you're looking ahead to those major expenditures!
As far as the wedding goes, my advice is to make it small. Our wedding was pretty simple, with a total cost (including wedding gown) of about $5k. My in-laws paid for it, which is part of why it was small--they couldn't afford much! Plant the seed now for your gf-possibly-future-fiancee to *rent* or *borrow* rather than buy a wedding gown. We've been married for 11 years, and the gown has been outside its box exactly once since then (when my wife's brother was getting married and his fiancee asked to try it on in case she wanted to borrow it).
Unless you're worried about a stock market correction, I'd say go ahead and invest the money rather than putting it into a bank account. If you have an emergency, you can always put it on your credit card while you wait for your investments to get deposited back into your bank account, and pay it off before it starts accruing interest.