The character girlfriend criticizes him and he says this:
俺が善がるだけしかできねぇってか!?
My reading is akin to "Are you say I only satisfy myself!?"
Then he later adds
死ぬほど善がらせたるわ!
From context I can gather he seemed to be saying he'll satisfy her needs to a crazy degree. But I don't this use of causative + たる. たる seems to be used after "noun" for capacity, but how is after a causative verb?
From context I can gather he may be saying "I'll show you I can also fulfill you needs/take care of you/etc"