Reason 1. Damon is played द्वारा the most beautiful guy ever(Ian Somerhalder), and no matter what they say he is hundred times better looking than Stefan its just a fact.
Reason 2. Elena is played द्वारा a one of the most beautiful girls(Nina Dobrev)
Reason 3. There both brunette and tall and both are extremely hot and that makes them look amazing together.
Reason 4. The reason DE aren't together is why we want them the most, if Elena fell for the bad boy first it wouldn't make much sense because Elena is smart so she wants someone thats good for her, which is sadly Stefan, looks doesn't have any thing to do with it. If both were good boys and she had to choose she would obviously pick Damon:P but she doesn't and thats probably because Damon can be an नितंब, गधा sometimes and thats understandable.
Reason 5. They have a lot of tension between them, the way they look at each other. When there really close to each other they never smile, they just gaze sadly which pumps up the tension.
Reason 6. Every scene they have makes us wanting more, like they act like there about to किस and have this weird romantic moment but they ever act on how there feeling.
Reason 7.When Damon started falling in प्यार with Elena he started changing into a good guy for her, that means he really really loves her, because he wouldn't change for anybody else.
Reason 8.The reason he fell in प्यार with her was because she was the only person who actually starting caring for him and started to see that there was good in him, and no one else saw that. These are just some reason why there so amazing togethertheres about a million more. These are just the main:P