Because
1) those two ships are cannon

2) I love Drarry so much I don't even care if it's a ship 

3) ITS JUST TOO CUTE I CANT EVEN I MEAN JUST LOOK AT THEM CUTENESS OVERLOAD *shoves a bunch of those books into your hands*

If you haven't got it yet, I'm a fangirl. Well, at least I have someone to fangirl to (just imagine two girl screaming and squealing about something while the rest of the class watches then in total silence)

Yup. You got it, it's us.

AND NOW I PRESENT TO YOU MY BUDDY, a_aisya