i woke up to see my dog missing huh? Where could it be? I went down to see the door open meaning my dog could have gone out

*I kept on finding him and even printed a "missing dog" and sticked it to everywhere but nothing, its been only a day since my dog is missing but then someone doorbells

*I open the door to see who it was "hey is this dog yours" i was so happy to see my dog heeseung "thank yo-" i stopped talking when i look to see who it was, and its heeseung, my ex.