I will say this in cases of sexual harassment and other forms of harassment its more than the physical aspect, there is often a power dynamic that comes into play.
That's why when we hear of more prominent cases such as celebrities like Harvey Weinstein the issue was a large difference in power dynamic. the difference between the people's respective power levels in that organisation.
In your case there is little context for me to give a better opinion other than there may be more power dynamics involved. Furthermore there may be peer pressure/social pressure and a stigma attached to "ratting on him" or "calling him out". I don't know B - is he powerful? his parents? is he the high school quarterback? the captain of the basketball team etc etc those things can add to a difference in power dynamic.
For the females - again I cannot give anything more than a general opinion on their actions because the actions by selves do not indicate wanted nor unwanted action towards B because we see it in other cases where a victim has "suffered" numerous times at the hands of the perpetrator but were too scared to say no. Domestic Violence victims often suffer a lot of abuse even though its certainly unwanted but only come forward after a long time due to family and financial and social pressures.
Then from the perspective of B - yes he may be still doing this because the females still engage with him, hang around him and do not actively distance themselves from him so in his eyes the "unwantedness" may amount to mere playfulness...and again without knowing more its hard to classify his actions as SH or not
. I see this guy as very toxic and I don’t understand 
