I can't see why it's bizarre. When I shared flats with people, nobody ever felt the need to go and hide (or ask a flatmate to make themselves scarce) - we just would all chat together.
You think a chocolate fountain is suggestive for later - so I'm guessing you don't have kids. Chocolate fountain is also a great way to keep kids happy and engaged.
Don't read so much into it.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.