Non-US visitor looking for romantic places in N Jersey

Hey everyone.

I am British and I visit the US every couple of months to be with my American girlfriend. I am planning on proposing in October, and I would love to know some really romantic places I could go to do it.

I don't know the state that well. We are up near Newark airport, but a drive on the turnpike isn't out of the question, just nothing more than maybe 45 minutes.

I thought of the Liberty House in Liberty State Park. Can anyone tell me if thats a nice area at night, looking out on to Manhattan and the Hudson.