I feel like something like this has been prompted before a while ago. Ok so Matt's excuses for his injuries while being a vigilante are pretty classic abuse excuses 'I fell down'etc. Now that Foggy and Karen know he is a superhero they attribute all of his injuries to superheroism and he lets them because he is in denial about the truth: his girlfriend who everyone loves is physically abusing him.

He blames himself of course and thinks any punishment he gets he deserves because after all his girlfriend is so nice and sweet....most of the time. So clearly when she is angry and hitting him she must be right to do so because nice and sweet people don't hit other people for no reason. Plus she is smaller than he is so it would be wrong to defend himself from weaker aggressions than he sees in Hell's Kitchen every day.