Depression isn't exactly rare - according to
NIMH around one in fifteen US adults experience depressive episodes in a year. Around one in twenty five experience severe anxiety (
NIMH again), and estimates of self harm vary between one in twenty five and one in a hundred (
Journal of the American Board of Family Medicine). If he's starting with the sexual stuff on day one with multiple targets and carrying on for almost a year, as per the article HomogeneousCow linked, then yes, I can expect him to consider mental health conditions like this. Best case, with ten women (again, per HomogeneousCow's article), he's got only a fifty-fifty chance (##1-(14/15)^{10}##) of not picking one who's depressive sometime in that year. Even assuming there's no correlation between being harassed by a tutor and depression.
But we can, and do, insist on certain basic standards that everyone must adhere to - and we employ police forces and courts to back that up. Are you arguing that we are wrong to require some basic expectations in certain cases? If so, what cases? How much eccentricity translates to how much reduction in expectations in what areas? Should Lewin be excused theft, or assault, were he to commit these? Murder? Or should he be held to the same standard as everyone else?
Or flip it around. Self-harm, anxiety and depression aren't straight-up healthy behaviour. A little eccentric, maybe? Lewin engaged with Harbi - now he's got to put up with the consequences. After all, he cannot complain when she blurs the boundaries of the mainstream...