I think Elain likes Azriel. But Azriel, I mean he's clearly attracted to her, but I think his feelings stem from 2 reasons
1. Elain's sisters are mated to his brothers. And he wants what they have. Her sisters chose his brothers! Mating bond or no mating bond, This male has been alone and aloof for 500 years, he just wants someone to want him forever. That brings me to my second point
2. Elain shows interest in him. This added to the first point makes him think she's the one.
I do not think Az's shadows disappearing infront of Mor or Elain is a good thing. They are a part of him. And these 2 females are someone their master has feelings for but (I think) they make the shadows uncomfortable.
And that's nooott a good thing. When we read the parts with Gwyn, there's just soo much chemistry there.
Point number 1. Az is hella competitive and so is Gwyn. Her challenging him is something he finds amusing.
2. Say what you want but I think unknowingly Az is comfortable around Gwyn. His humour comes out around her. She makes him feel lighter.
3. Shadows! His shadows literally touch her breath. And when he leaves her, they're singing. Singing!
On a side note. It's been repeatedly mentioned how Elain doesn't fit well in the Night Court. She's literally described as a Ray of sunshine. Sunshine belongs in the day court!!