They'll need a few days to sort out a pecking order now that they've been moved to a new tank. They'll settle down. The female could have had a falling out with her potential mate before they could spawn.
Could be the move upsetting things if they were actually a mated pair. Or, don't know whether you bought an established group that had already been together in their current combination, but it could also be that she's been separated from her former mate.
Ime with red head tapajos, new pairs may bicker off and on for a while, often settling into a good pair in time. But that depends on the pair, tankmates, etc. They could also eventually decide they don't like each other, though most of the time they eventually work it out ime. Also, females bickering or an outsider female harassing the pair isn't unusual when there's extra females ime.
Your call or preference, really, or you can adjust to how they're doing together. I've done it both ways. Often, when you have odd (extra) females, they tend to fuss around competing with each other or trying to be one of the pair, but a good or dominant pair can deal with this ime and it doesn't necessarily disturb them much-- maybe if the odd female out was too large or aggressive it might be more disruptive.If and when a pair forms, should I reduce the group? Or will the remaining 3 learn to live peacefully in the 125G with the pair?