The 1st-level Sor/Wiz spell feather fall says that
When the spell duration expires, a normal rate of falling resumes.
As that can't happen if the spell's target isn't falling anymore, falls taking multiple rounds may exhaust the 1 round/level duration of the spell before the fall ends, at which point the target resumes falling normally.
However, one can't exploit the 1 round/level duration of the spell feather fall to make
multiple jumps because the spell also ends upon landing.
In other words, the spell only allows one landing, but until that landing occurs the duration of the spell is 1 round/level.
The wizard might not have any choice but to join the leaper in the abyss. Assuming he doesn't want to jump then at the last minute cast on both himself and the leaper the spell feather fall then teleport himself back to the starting destination, the wizard may want to make things easier by just giving the leaper a wand of feather fall (750 gp; 0 lbs.) (if the leaper can use it but beware its 1-round duration—"Wait for it! Wait for it! Now!"), boots of the cat (1,000 gp; 1 lb.), or even a ring of feather falling (2,200 gp; 0 lbs.).
This event is, essentially, the falling character making a journey of some length straight down. Any method of long-term flight will be superior to the spell feather fall, which is intended to save hapless adventurers from death by pits and cliffs not near-bottomless abysses.