Fast is a relative term. In the time cycle of the universe, a millennium would be considered fast.
There are so many variables that it is impossible to say how long it will take a spirit to act on your behalf. It takes as long as it takes.
Is the target protected?
Is the target’s will stronger than yours?
Are there other forces working against your magick?
These are all things that could hold up the result. So could your impatience, aka “Lust of Result.”
Personally, on difficult tasks, I will generally wait one month for a sign of progress, and two before considering the ritual a complete failure because sometimes there is movement behind the scenes where it can’t be seen, like your target couple being happy in public, but arguing behind closed doors.
However, after two weeks, it is fine to call the spirit again and ask for an update. Maybe ask him to provide you a sign of progress to set your mind at ease and help you let go.