I agree with you. Dev needs to go through the same longing and pain which Sona is subjected to.
Pre confession, it was her who cried day in and out. .and Dev just got her love without much efforts.Even after confession, It is mostly Dev who walks out or rejects Sona's views. . Sonakshi is the one who makes up for it. (Apart from the barish sequence, but there too Dev was leaving after saying how he is a complicated man and It was Sonakshi who stopped him)Just accepting you are imperfect in not sufficient at all, you need to work on your flaws specially if you are aware of them.Dev should know how lucky he is to have her.