That would have had the opposite effect.
Sometimes it does
That is not a sometimes type thing. When someone is insecure and dont love themselves and you try to make them jealous, they most likely wont get jealous they will just feel more insecure. So many people try to make people jealous instead of helping them with their insecurities. They so eagered to be chased instead of doing the chasing. You think you would get them in the end but all you'll do is make them fell as though they were right to feel insecure for the the start.
I dont mean to snape at you but that is a very toxic mindset.
But how would you know that the other person is talking from his insecurities not from his thoughts, I mean in this situation we know about his past, but it's not like that in most of the cases , sometimes you need jealousy so the other person would move
But that's how I've always been
I would definitely go for making him jealous by hooking up with the brother I would never thought that relationship could be resolved this way