Responses
This is good theory or they have very similar pheromones.. but I think he would have wanted to make model his sooner and not wait after the marriage news? I think he just wants to stir the pot.. He as young omega probably destroyed his parents relationship or something..
Ahh but I hate this trope. After the main couple gets together there are people trying to break them up.

Wait so he's the son of his "fated mate", and he's asking if your fated mate were to appear in front of you or your partner what would you do essentially. Could it be he was actually supposed to be his fated mate and his smell maybe just rubbed off on his dad and mc got confused and that's why the old fucker never cared about him? Just a thought