Disclaimer - I don't own Melissa and Joey and never will. No copyright infringement intended.
Mel is not in love with Joe. No, really. She's not. At least that's what she keeps telling herself. At night, she imagines the four of them being a real family. It's a nice thought that she won't tell anyone. Mel swears that Lennox knows about her feelings for Joe, though. She keeps sending her knowing looks and mentioning something about them being a couple.
Joe will never feel the same way for her. Why would he? Her brother-in-law is the one who ruined his life!
Mel will never tell Joe about her feelings for him. It's easier that way.