SUBREDDIT: r/relationships
TITLE: My (F 22) boyfriend (M 23) of a year is constantly talking to other girls
POST: So my boyfriend and I have been dating for over a year and a half. It's been a wonderful year and half. 

We have had our ups and downs but we've always been able to get through the rough patches and we are even  at the point of talking about marriage. Last week he even talked about getting a ring. But here's the problem. 

During those rough patches, the reason why we were having them is because I've caught him talking to other girls. And not just friendly talk. So after the second time catching him. I gave him a choice either me or them. And he apologize and said he was acting stupid and selfish and said he would never do it again. That was 2 months ago. 

Tonight I saw on his phone that he was using a dating app to talk to girls. Neat right. My stomach is in knots and I feel like complete shit. 1) because he went back on his word 2) because obviously he's "sexting" them 3) I'm obviously not enough for him. 

So I need your advice. Should I give him another chance and try to talk to him about it? Or should I just break up with him and if so how do I go about it? 

It just sucks cause I love him so much and I thought he loved me too.
TL;DR: 
caught my boyfriend talking to other girls after asking him to stop now I don't know whether I should break up with him or try to work it out.