Sisters Forever... Unfortunately

*In the middle of the night*
Sal: I love you, guys.
Everyone: *silent*
Sal: Dili? Are you sleeping?
Dili: *smiling* No! Now stop talking to me. I want to get some sleep tonight.
Sal: ... Do you love me?
Dili: *silent*
Sal: Fine. Ally, do you love me?
Ally: *sounding annoyed yet amused* Be quiet, Sal. No one wants to hear you talk.
Sal: You're rude. Mari, you sleeping?
Mari: How can I be? You guys are so loud, my ears hurt.
Sal: Blah, blah, blah. Ellie, do you love me?
Ellie: *fell asleep hours ago*
Sal: I feel unloved.
*At the same time*
Dili: Because you are!
Ally: Because you are!
Sal: Meanies...

These sisters are best friends, yet worse enemies. They love each other, but they're always making fun of each other. How does that work?