@Shivika_Malhotra First of all I'm sorry.. I've just seen this message of yours.
Lia has always been pampered and Rian is her older brother ofc he will be protective of her, on top of that Rian wasn't oblivious to the fact that Aksh is deeply involved in mafia things so if you think from his perspective.. and from how the author has characterised him.. it is sane. I mean no brother would want his sis to be involved with some mafia guy irrespective of the fact that Aksh and Rian are good friends.
As for not sorting it out, Rian's character has been built that way, he might have asked lia to choose, but it was the circumstances that actually had her to leave Aksh!... Because if she wasn't kidnapped.. Lia would have definitely found a way to convince Rian. Rian had always wanted her happiness first..but as an older brother who has always been protective towards his sister.. it was actually fair.