Lyric discussion by blondxgurly 

Cover art for Lonesome Day lyrics by Bruce Springsteen

i think its about a guy who just broke up with a girl (possibly got dumped by her)because there was something about her that he didnt know, like a different side of her. and he is saying that he is lonesome, but he knows he can get through it. he is saying that she bettter know what she is doing before she does it, because it is something she might regret