IDK, as othes have pointed out... Luke did say she was Beautiful when he saw her in the hologram video from R2D2. But when Leia kissed him I believe she did that to piss Han, off and hide her feelings for Han. Other than his compliment and her using him, I think they were just really close friends who had an intuition they couldnt figure out until Yoda told Luke there was another Skywalker
Yes! Leia and Luke were very close. More than "Friends". They were probably the Better Couple. And they did More than Flirt. And she wasn't just making Han jealous on Hoth, Leia really didn't care for him! Han wasn't even "into" Leia, Nor she "into" him"! Leia and Luke loved each other from IV TO VI. Until they were forced to become related. Otherwise who do you think Leia would choose. Luke or Han? Luke! was the Original concept for the story, before George Lucas changed it AGAIN!! Leia and Luke weren't supposed to be siblings!
I always thought Luke had a crush on Leia at first, but she didn't reciprocate, and Luke's feelings downgraded into close friendship not long before he found out she was his sister.
I'd say Luke definitely liked Leia from Ep. IV to early Ep. V. After his time on Dagobah, Luke seemed to have more important things on his mind.
I don't think Leia was ever romantically attracted to Luke. By Ep. V, evading Imperials while onboard the Millenium Falcon, Leia was finally falling for Han so from that point on, she was definitely not thinking of Luke as boyfriend material.
I think Luke might've had a crush on her at first but I think he admired her feisty attitude and the fact she was a natural leader. Little did he know that she got these traits from her mother Padme and her temper from her father Anakin.
I think they did have a little something going on. Read Splinter Of The Mind's Eye and you will see them alone together. I have read it well over 100 times. Pretty short book so it won't take long.