They don't know about Mark and Youngjae.

They don't know about how close they've gotten since they first met.

They don't know about the underlying meaning behind the way they look at each other.

They don't know about the countless smiles that were caused by the other.

They don't know about the secret hand holding that goes on under the table, nor do they know about the sweet kisses that are stolen when nobody's looking.

They don't know about how they feel when they're being shipped with other members.

They don't know about their fights, which usually end with someone (or maybe even both of them) getting hurt. 

They don't know about the apology hugs and kisses that are responsible for patching up their quarrels.

They don't know about their tender and gentle love-making or the way they would lace their fingers together as they lulled each other to sleep with the sound of the other's breathing when their love-making came to an end.

They don't know about the quiet nights they spend together, holding each other in warm embraces, each taking comfort in the way the other was holding them.

They don't know about the deep and meaningful conversations they have when they're alone, some of which were about their future together. 

They don't know about the "forever" that they promised that one night when one of them suddenly said, "Let's get married someday."

They don't know about how close they held each other that night either. 

But most importantly...

They don't know about how much they love each other.