Pathological altruism is altruism taken to an unhealthy extreme, such that it either harms the altruistic person or the person's well-intentioned actions cause more harm than good.
pˌæθəlˈɑːdʒɪkəl ˈɔːltɹuːˌɪzəm ɪz ˈɔːltɹuːˌɪzəm tˈeɪkən tʊ ɐn ʌnhˈɛlθi ɛkstɹˈiːm, sˈʌtʃ ðˌɐɾɪt ˈiːðɚ hˈɑːɹmz ðɪ ˌɔːltɹuːˈɪstɪk pˈɜːsən ɔːɹ ðə pˈɜːsənz wˈɛlɪntˈɛnʃənd ˈækʃənz kˈɔːz mˈoːɹ hˈɑːɹm ðɐn ɡˈʊd.