I have been listening to the song Aaj Se Teri for a few days and it has become one of my favourite songs.And today I was just humming it and it came to my mind that I should know the meaning of this song, so I went to YouTube and saw its explanation.
I watched the entire song explanation but I liked one paragraph so much that I want to share it with you.
This song is written by Kausar Munir and sung by Arijit Singh.

So imagine a boy and a girl, how they live before marriage and now imagine a boy and a girl after marriage Now you will see that the boy looks the same even after marriage as he was before marriage.Now you will see that the boy looks the same as he was before marriage, even after marriage. But if you look at the girl, she looks different after marriage. She wears a saree, wears bangles on her hands, vermillion in the parting of her hair, mangalsutra around her neck, all these are the signs of a married woman. And this paragraph represents that how a boy will live after marriage.

Tere maathe...

Tere Teri Mathe ke kumkum ko main tilak laga ke ghumoonga .

In this line it is said that he will apply the kumkum from your parting on his most visible place which is his forehead. Before marriage he used to go to a temple and apply tilak in the name of goddess but now he has become completely devoted And now he is calling her his godmother.And now he considers her his God.
Next line is

Teri Baali ki chunchhun ko Main Dil Se Laga ke jhoomoonga

Every woman creates a new sound with her earrings bangles or anklets. And even in a crowd of millions and thousands, if she is coming from a distance, you will recognize her in your subconscious mind that she is your life partner just only by the sound of her earrings and anklets.

Meri chhoti si bhoolna ,Ko tu nadiya main baha dena

Tere jude ke phoolon ko me apni shirt me phenunga.

If a couple live together, there will be some conflict. And assures that the mistakes will be minor. And if the girl keeps those things suppressed in her heart then the relationship will weaken and misunderstanding will increase. So the boy says to her that all the mistakes should be flow away with the river water. Because the water that flows into the river never returns.
When the boy brings a gajra in his shirt pocket for his wife to wear in her hair . The fragrance of the jasmine gets on his shirt, he will roam around with that fragrance in the feeling of his wife.

Aaj Se meri sari raatiyaan teri ho gayi aaj se tera din mera ho gaya .

When the husband is out of the house for work the whole day, he will not be able to give time to his wife, but when he comes home, he wants to dedicate the evening time to his wife. And in return he will ask his wife how her day was today and they will spend their evening talking like this.