Okay so I'm not too sure what works in the serial world and in other cultures so I'm saying this from what I have understood about indian weddings(Gujju ones are slightly different so using that to explain and mine)
Most of the rituals at the beginning are to actually ward of evil, "invite God" to shower their blessings and let the wedding be completed in peace.
The agni(fire) is actually the most significant as they usually say that the fire is the sole witness of being bound in matrimony( Fire being derived from a never ending force i.e. Sun) and that as long as the fire is not extinguished, the wedding is considered sacred for the world, However, as Abhi put the fire out before they had completed the pheras, it might not count.
The pheras themselves have significance (as he sort of mentioned in the corporator episode) in that you are stating how with body, mind and soul you're joining as one. Incomplete pheras(what looked like just one) will then mean that they have not been joined in marriage.
Then there is the actual mangalsutra and Sindoor. Those also have importance in that they are physical aspects binding the two people together, hence why women stop wearing sindoor if their spouse passes away. I'm not too sure but I think someone I know mentioned that it is to signify that your husband is alive(red like blood flowing through him) and till he is alive, he will always protect you(that's why it is on the head) {This might not be true. just mentioning what I have heard}