Will try to answer your question Moni.. but right now its difficult to say for sure what that black vest means because story can still change in many directions .
1. that black vest may not mean anything... that is it has no significance attached to it as far as a symbolism is concerned, as we all know many montages and promos are misleading and doesn't really make much sense as far as the future story is concerned... so it may be just a fashion thing without any significance.
2. some people have pointed out that it indicates that Asad will misunderstand Ayaan and Zoya while they are innocent (they both wearing all white).. and the Mu will be created by Tanveer.
I really had doubt regarding this theory because i felt that Asad and Zoya are too much into their relationship for Asad to have a doubt regarding Zoya like this and for Asad to think that Zoya and Ayaan are having something behind his back... and yesterday it was proven that he will not doubt and MU them this way..
And i think in future also he will not , although Tanveer may still try to put doubts in his mind.
3. The most plausible theory i have for the black vest is that Asad will later fight with everyone for Zoya.. he will have a fight or disagreement with Ayaan as well.. his angry look at Ayaan in the montage indicates that.. but he doesn't give that look to Zoya... so when he fights with the family and the society for Zoya, he will be declared by others as a negative person and labelled as bad... Niki and i had a discussion on this and i remember that Niki mentioned the appropriate word for it - black sheep.. he will be declared as black sheep of the family... how all this will play out is to be seen... i believe what is going to happen between Nikhat and Farhan and haseena Bi's drama will also have a major role to play...
If at all there is a significance to the black vest, i think it means this... but i may be wrong.. lets see..😃
PS.. this is an answer to a question, moniloveasya asked me on another thread.. the answer became too long.😆.. and also since i think this black vest of Asad is a thing many here wonder about, i thought i will post this answer as a separate post..
Do share your views..😊