General thoughts
The story is pretty straight forward there is no suspense there. Sorry my intention is not change your story. But make it little more like a real thriller.
The Hero should not know that Salma is dead.
She can appear to him in Antarctica; convince him that she came to see him
He should know only at the end that she is dead. When he himself dies when he comes back to india. Just to make the story spicy.
I recommend you to watch 36 china town
https://www.imdb.com/title/tt0477252/?ref_=nm_flmg_act_46
Your Scene1: Should establish the Geologist Abu doing a TED Talk technical presentation ( for 2 min). Some sponsor inviting him to Antarctica for upcoming research project.
<< showing antartica in a film might be tricky unless you can photoshop the scenes>>
The marriage discussion between Salma and Abu can be spiced up a little bit
Abu says - in the western countries people live together without getting married. Marriage is not a necessary institution any more.
Salma - insists on the sanctity of matrimonial institution.
<< I can send you a good write up on these points if like ... just a thought ... instead of just saying because Abu's work he is postponing the marriage>>
In your scene you might want to include the last call; where Abu confesses and agrees to marry before starting from Antartica.
In your scene 6 : Abbas should suspect Rukmini playing pranks on him; when he is confronting her he should get text message from Salma; Now the real mystery begins;
Abbas should not be fainting in the scene as he should be still assuming someone is pranking and hacked the cell phone. He should be reaching out to cell phone company ( some know aquaintance). They should see the records and confirm that there is no evidence that the messages and calls are coming from Salmas phone to Abbas.
Scene 8: Abbas meeting her in person(though she is dead) sort of takes the thrill away from the audience. Or It has to be another person .. everyone else see the other person except for Abbas she appears as Salma
<< This scene needs to be really thought through .. i am just sharing some random thoughts>>
I think until she is dead part the story is going fine.. but need to give a new twist to the story it cannot go on a regular pace. You have the emotional content right but its not gripping.