Because she is an idiot. I hate that she's with Damon even though he does stupid things all the time to her or towards her family and friends
She picks Damon because Stefan is going to do horrible things to her and that will eventually stop Elena from having any romantic feelings toward Stefan. There are some other reasons too but I don't want to spoil anything. Hope this helps :)
Because she'll fall in love with him, no matter all his flaws, she sees the good in him. But I must agree with previous comment, their relationship became lame and they both continues to do stupid things... I envy you, you're only on the first season, it was the best...
I just wish Katherine comes back!
im only on the 1st season but ive read on the internet that she will pick damon over Stefan. Why does she still pick him after everything she has learned about damon?