Boyfriend

Okay guys so latley bf has been talking to this girl to make her feel better bec her ex boyfriend ( my bf friend ) dumped her and he feels bad so he’s been texting her day and night , morning throughout the day , during school , AND WHEN WE’RE ON THE PHONE. We got into an argument about it today bec I was getting jealous and he understands but he’s not going to stop talking to her bec everybody else stops talking to her so she has no one and he doesn’t wanna be like that but all the other girls that I don’t like he stops talking to them an in instant but this one no ? WHAT SHOULD I DO !? Should I feel worried ? I kinda feel worried , I don’t wanna lose him and we’re making 8 months on Monday