Some fish are just jerks. If you mix male and female mollies the males will harass the females, so you want to have more females than males so the harassment is spread around. 1M/3F is usually considered a good mix. If you continue to have problems after increasing the mix, then we go back to some fish are just jerks and you should consider separating the male.
Be aware that mollies are livebearers, and livebearers breed copiously. You will get babies, if there is nothing to predate on the babies, you will get a lot of babies, and then the babies will quickly start breeding with each other, then you get a population explosion and whatever tank you have quickly gets overrun with mollies. If thats not situation you want, then separate males from females. Also, female mollies store sperm for up to a year, so once they have been with a male they can continue to produce fry for a long time even after separation.
From your other post you are keeping the fish with frogs. This isnt usually considered a good idea. If for instance your fish get sick, the medication used to treat the fish will kill the frogs. Also mollies are really brackish water fish, not freshwater.