It depends. Usually a week will be fine for a cool down period.
After that, if she start msg u, then u should apologise. If both
parties are stubborn, then i guess the male has to give in 1st and
initiate an apology. Pride n ego is nothing worth 1 lah...
But the thing is, why get into a situation when a couple quarrel?
Yes sometimes quarrels can spice things up and trigger emotions and
show that both parties still care for each other. Coz if one is not
even bothered to quarrel, it means he/she may not even give a damn
about the relationship anymore. However, every quarrel means there
will be "scratches" in the relationship and it will come a time
when the war may last forever...Means one party may think it is no
use trying to salvage the relationship anymore. My fren once told
me that each quarrel causes a dent in the relationship and it is
not healthy in the long run. So, think about it. It's okay to make
mistakes, but sometimes too much of it is not good.
Think what is the cause of the quarrel and find the root of the
problem. That would be a better solution.