Should i break up?please help

I am with my bf for almost a year we have been living together for about 5 months,he is everything i hoped for about one person,this is his first relationship even tho he is 22 years old,he never done anything with a girl before me.

When we met each other at first i was terrible towards him i didn t know if i wanted to be in a relationship with him in that chaotic time he made a mistake and dmed another girl that isn’t from where I lived just for *** and giggles (said to her what a view ;))with his friends and after i found out about that i was so heartbroken and we spoke about that how it hurts me and my boundries and now 8 months later while he was checking *** i saw another dm from another girl from another country,even tho he didn’t filrt or anything it hurt me pretty bad,i have to say he is a Youtuber so he got lots of request,and he said he didn’t exactly remember conversation we had or boundries i set and that it got mixed up i have said that if is someone from youtube that wants to talk that is okey with me, this girl said she was from youtube but then asked him if he has gf and he said yes,he is not single and she continued that he is handsome he said thank you and the “do you have snap" he said “no” but it bothers me that he even reply,cuz conversation wasn't about youtube he then stopped replying after she said "do you wanna play" only then he saw that conversation wasn't okey anymore,(btw he doesn't know how to use snap and he didn't use that so when she asked he just said no)

He is really pure in his heart i cannot explain it i know he is,no one can know that until u meet him,he just doesn’t think sometimes and makes stupid mistakes that hurt me really hard…idk what to do,i love him so much and we get along so well i don t know if relationship is doomed :(