Yeah that one is male, you can tell by the extended/pointed dorsal and anal fins. Females have rounded fins, and I think they are a bit more chubbier. If your sick FM heals you can keep him, but if you want a pair, just add like 3-4 more FMs and you will get a pair.
You cant say for sure though if the healthy FM is bullying, unless you actually observe it. A bully fish will bully all the time, not just when you arent looking.
The sick FM I cant tell its sex, maybe when/if it gets healthier you can find out.