When it comes to dealing with loss (bereavement, the end of a relationship, the loss of our job or, in your case a failed house move) our mind can conclude that the thing we have lost was so integral to our idea of what happiness is that we can never be happy again.
This can lead to depression. Our mind perceives no possibility of future happiness so they stop trying. The weighing scales analogy is worth considering here.
When we want to weigh out ingredients to cook something we place a bowl on the scales and hit the zero button so that the weight of the bowl does not confuse our calculations. Then we add the ingredients and the numbers go up; were we to remove the bowl the scales would read a minus number. To continue weighing anything accurately we must hit the button to zero the scales once more, now the bowl isn’t there.
When we have a tragedy in our life we can be plunged into depression because our happiness levels now read a minus. Any attempt to improve our life would result in slightly less of a minus... but a minus all the same.
Depression is when we don’t see any way of getting back to zero. A person’s ability to move on from tragedy depends entirely on their ability to adapt to where they are now and to effectively ‘zero the scales’.
If we can accept where we are today (minus that loved one, or that relationship, or that house) then we can start to once again build on our happiness levels.
Human beings are in fact excellent at resetting the scales and adapting to new circumstances - we do it every time we improve our situation or circumstances but very quickly take that for granted.