What is the word for a man who keeps returning for other people to abuse him?

Solution 1:

glutton for punishment is fairly popular

http://idioms.thefreedictionary.com/a+glutton+for+punishment

http://en.wiktionary.org/wiki/glutton_for_punishment

Solution 2:

You are probably referring to a case of masochism:

gratification gained from pain, deprivation, degradation, etc., inflicted or imposed on oneself, either as a result of one's own actions or the actions of others, especially the tendency to seek this form of gratification.

masochist:

a person who is gratified by pain, degradation, etc., that is self-imposed or imposed by others.

Source: http://dictionary.reference.com

Solution 3:

I think masochist fits in the respect that the subject is deriving some sort of pleasure from the deprecation, but based on that he keeps returning to that situation as if he is connected to it, the term dependent comes to mind.