Wait, I'm confused about the ending of chapter 3. Can someone explain?

I don't know, I was confused too but maybe... she's just using the dude ? Like... maybe (on her phone) those are messages to other dudes who she also goes out with..? Maybe ?

yea, we see it on the last chapter as well, she's a cheater who goes out with lots of people. the last panel of ch3 is her phone full of guys's names.

Dang, I felt bad for her lil bro, but that ending makes me think that he's happy with it or I could think otherwise.