US Housing Affordability Downtrend
When rates go down, buying power goes up. This means if the house prices stay the same - you can buy a bigger house or have a lower payment. Your choice.
Because housing prices are often bid up when rates are low (fixed supply and greater demand) your 'savings' on payment is used to finance the larger loan for you to buy (what is often called a 'sellers market'). In time this shrinks the number of buyers, and things flip to a 'buyers market'.
We are now back to 2007 affordability.