What is the meaning of [When the wolf comes in at the door, love creeps out of the window]

The ‘wolf’ is poverty. When a young couple marry without enough money to keep
them in a manner to which they have become accustomed, this is called ‘love in
a cottage’. The love lasts as long as the money, but not a day longer, so the
proverbs says. So, you’d better First thrive and then wive.