Jongin would be a little jealous but mostly curious. He would ask you who this man is and want to know if he is someone who he should be worried about. Once you tell him who the man is and tell him why you two were walking side by side, Jongin would relax. He would trust you completely and not doubt you at all if he really loves you.
"Should I be worried? No? Okay." -Jongin
*****
jongin on multimedia, ill post chen on the next chapter.