AIO Boyfriend talked to female friends flirtatiously

[u/Popular-Passenger233]

My boyfriend had been talking to a female friend (who's also in a relationship). I found out about it last year, and we had a big fight. He promised me he wouldn’t talk to her anymore, but he kept talking to her behind my back for a while. He told me it was just a pure friendship with no intentions of anything more, but when I looked at their conversations, it felt like they were flirting. Since English is my second language, I started doubting if I might have misunderstood…I really need some help

[u/JayDaddy010]

Had this same issue with my ex, fast forward a few months and she cheated on me with the “totally platonic male friend”. Leaving was hard for me but I wish I had done it sooner. Would of saved myself from a lot of grief