Arthur and JoAnn are old friends and both have feelings for each other. But both are on opposite sides.

He has his concerns about JoAnn. Despite being 'enemies', Arthur is one of 2 others JoAnn confides in (and are the only ones allowed to refer to her by her actual name, instead of the pseudonym "Heyuu Girl"). He knows about her previous relationship, and how Nise cheated on her (even if Heyuu does have some fault). He knows she ultimately keeps them around because she has a grudge against him and Lauren (although has absolutely no ill-will for their daughter, Erin). He knows that she had her own social issues back in college.

Perhaps a bit impassioned, he wants her to simply stop and to come with him. Even if he is rather poor and doesn't have the resources Heyuu gained, the two of them know it doesn't really matter. She's putting herself in an environment to cause her stress, purely for motivation to remain a villain.

All JoAnn can ultimately say is that she's in too deep, and this is just how things have to go.

And Arthur doesn't understand her reasoning.

Just wanted to do something with the two of them confronting each other