Talk about dramatics. I keep my wild bettas together in a tank with males and females all mixed in. Only the dominant pairs of mine spawn, the others just swim around doing various fishy things.
Surely with all the pheromones floating around in those tanks my unmated females should either be stressed, dead or exploding with eggs? None of them are. They are all lean, mean, eating machines.
My male who lives in my sorority has built a total number of zero bubblenests in the entire time he has been in there.
Here is a picture of him floating merrily in his little breeders' net. The females completely ignore him. The only interest he holds for them is during feeding time when he gets fed and they don't.
I have never ever had any issues with egg-binding or stress because my males and females share tanks. I have over 70 odd fish with some very rare and sensitive species of betta, so don't think I am some newbie who knows nothing.
I think that as long as there is no way for the male to get in with the females then there is minimal danger in keeping them together. I think there are worse things on this forum than a male and female sharing the same water.