Regarding the OST:
The first two lines seem to be Shamsher, then from tera saaya its Mehak...
What I think:
He's singing that she's hurt him coz she won't accept his love...then she says "tera saaya mere aage meri awaaz peeche hai" aka (what I feel) he's walking ahead of her, he's kind of become her "shield" but awaaz peeche to me feels like he still doesn't really hear her out.
Then "tera dil koi patthar hai meri jaan iske neeche hai"...he loves her but she doesn't reciprocate toh jaan atki padhi hai Shamsher ki, pain feel ho raha hai.
"Meri saansein mujhe de de, khudara mujhko jeene de": Mehak wants him to leave her and get out of her life. She's forgotten what it feels like to be alive.
"Meri faryad sunnle tu, kabhi sunnle meri arzi": Here it feels like he's arguing with her but more like a plea, that give me ONE chance, hear me out, but she doesn't budge.
Ab jab iske baad "main sau sau haari haari" aata hai na, tab I get a feeling Mehak finally gives in and falls in love with him.
Toh second antara is their push-pull relationship after marriage.
