<human>: Could you distill the essence of the text into 1-3 sentences?

My best friend and his girlfriend first met 5 years ago. I had known them both for years, and introduced them to each other at a Christmas party. He fell for her hard and fast, and ended up making advances too soon. She wasn't ready for a relationship, so she broke contact with him. Then, on New Year's Day this year, I accidentally invited both of them to the same event. They hit it off, and they've been dating for about two months now. 

The relationship has been moving extremely fast, so I honestly wasn't surprised when my friend said he was thinking of proposing, but I thought he was talking about sometime in the distant future. Turns out, he wants to propose this Sunday, the day of their two month anniversary.

I am against the idea because they are both young, both figuring out who they are, and they honestly barely know each other. My friend won't listen, and says that he wants to trust his gut. I'm lost as to what I should do at this point. What would you do if you were in my shoes?
<bot>: Young, impulsive 19 year old is about to propose to his girlfriend of two months. What would you do if you were in my shoes?