Yeh parent's approval is a big thing if you are planning to marry because you are pretty much merging the families, if they disapprove then you will ultimately have to make a choice between your parents and your partner. Personally I wouldn't tolerate rubbish like this from my parents and call them out on their bluff. I would tell them straight up that if they disrespect my personal decisions in life and as consequnce plan to move out, sell their house that's up to them and that will not affect my decisions. But that's just me, I'm naturaly resistant towards manipulation.
Don't cry, don't regret and don't blame
Weak find the whip, willing find freedom
Towards the sun, carry your name
In warm hands you are given
Ask the wind for the way
Uncertainty's gone, your path will unravel
Accept all as it is and do not blame
God or the Devil
~Born to Live - Mavrik~