My boyfriend’s friend’s ex wants to rely on him for emotional support

My boyfriend (24M) and I (22F) have been together for 1 year. He has a close male friend who recently broke up with his girlfriend because he cheated on her.

The girl called my boyfriend twice after the breakup, asking about his friend and talking about how hurt she was. My boyfriend comforted her and apologized on behalf of his friend.

At first, I was okay with it because I understood that she was hurt and probably needed someone to talk to.

But during their second call, she apparently told my boyfriend something like, “If I’m sad or crying, I’ll call you.” My boyfriend then asked me if I was okay with that, and I immediately said no.

He told me he didn’t agree to it and that he doesn’t want her to call him whenever she’s sad or crying. What bothered me was that he didn’t set that boundary himself when she said it. I told him I wished he had said something at that moment instead of waiting for me to tell him I was uncomfortable.

I’m not worried about cheating or anything romantic happening. My concern is more about boundaries, especially if she starts relying on my boyfriend for emotional support while she’s still dealing with the breakup.

I’d like advice on how couples can handle situations like this and set boundaries when one partner becomes an emotional support person for someone outside the relationship.