Your best friend making a new friend isn’t a subtraction. Hearts don’t have a member limit like group chats.

Jealousy between friends grows out of a quiet assumption that closeness is a fixed quantity being divided up. It is not. Somebody having another good person in their life takes nothing away from what they have with you, although the time may shift around, which is a different and much more workable problem.

When that pang shows up, name it as a pang rather than as evidence of something. Ask for time directly instead of testing whether it gets offered. And meet the new person, because the fear rarely survives contact.