He has always been possessive and insecure even when they were dating and then got married. He sees Sona as just his and no one else's. It is his way of showing love I guess 🤔 which I dont agree with.
Sonakshi is more level headed about everything. She does have feelings for Dev still but she doesnt show them the way Dev does. He makes it obvious. I wish they would make it clear whether they are divorced or separated.
If they are divorced Dev has no right to tell Sona what to do. She can have as many friends/partners as she wants.
For Dev when he forms a relationship that one person becomes his world. Sonakshi is his world and he wants to know everything. I dont know if anyone remembers after the confession episode he said to Sona that he wants to know every thing about her. Yes thats fine but there are some things that are only known to you as an individual.
This is where his possessive nature comes in and he cant control himself when he loves someone. He becomes obsessed with them. This is what is happening with Soha and now again with Sona when he sees her with Jatin.
They both love each other still but they are trying to hide their true feelings through anger and hatred.