A) make the person you still care about (and whom treated you like royalty) either feel jealous about your new relationship or
B) make the person you still care about call or text you to let you know you texted the wrong person, thus giving the pathetic texter a chance to try to weasel back into the textee’s life.
The texter usually pities his/her own life because of the bad choices made and desperately wants their old life back.
It’s a pitiful, pathetic mind game. It’s also an updated version of the 1980’s classic scam in which the pitiful loser (realizing the new relationship sucks) sends flowers to him/herself with a romantic note in hopes the person they still care about (but whom they walked out on) would see arrangement and get jealous.
Mike: "Oh, Tony. You know she’s still bangin’ that new jerk. She wants out, she wants you back, and she wants you to call her. That, my friend, was a pity text. Pathetic."
Tony: "What a bitch."