I've been having a hard time figuring out the line between mental and social, but here's kind of my take on it:
In physical combat, if you incur Physical consequences, you need medical attention to start recovery
In mental combat, if you incur Mental consequences, you need a psychologist or therepist to start recovery
In social combat, iff you incur social consequences, you either take steps, in game, to fix it yourself or it fades over time - depending on the scope of the consequence.
Mostly, if it comes to interacting with another person, then it is a social conflict. Social conflicts don't have to involve anyone else other than the target of the attack. For instance, if you're trying to ferret out the truth from someone, this would be a social conflict and consequences would revolve around that person giving up information. The consequences would probably fade shortly after the conflict as the scope of the conflict isn't far reaching and might not have anything to do with a persons reputation.
In a physical combat, if you're trying to convince a gangster/bodyguard to let you past to pursue his Boss - this would be social combat. If he fails and let's you go (if he conceeds), his more serious social consequences would be more far reaching because his reputation as a body guard would be tarnished. There'd probably be a reconing with his Boss as well. This last part might lead to mental stress. (Maybe if his High Concept revolves around being completely faithful to his Boss)
From what I can see, Mental damage and consequences are super rare and socially, is used in very rare situations (like an abusive relationship). So over a long enough span of time a person might suffer mental stress/consequences.