Your point is the reason this movie got a 7/10. As much as I reasoned with myself saying "Aravind is a guy whose mental state is prone to shifting constantly", I couldn't buy into his and Renu's relationship.
The film has to juggle his relationship with Swecha and his bubbling relationship with Renu and doesn't have enough in terms of time or story (in the second half) to carry it through. As you said, Renu's point of view is very understandable as in, she's looking for a newer better partner. Aravind cannot keep himself focused on one aspect of anything because of who he is. But their dynamic is one of one of them being the saviour and other one being saved.
There is a great way to do that but this is only passable. Once they get together, it smoothes out well.
With the film being a hyper-realised take on reality, I tend to give it a pass. Because when I've seen people get attention from the opposite sex for the very first time, they tend to lose all sense of control because it is a wholly different psycho-sexual experience. I like that the film used a narrative hook to show what most of us experience in our lives.
Sad to say it wasn't perfect. But the fact that it made you think about character dynamics, their choices, their mindsets and what you would have done in their shoes is what makes watching this film a worthwhile experience.
As you know, it is more than you can say for most films that come out on a weekly basis.
You know what we love? Love. No matter how many of the stiff-upper-lipped critics say the genre has outlived its welcome, we still watch romances, and they still make money. Simply put, man is a social animal, and social animals need companionship, or at least stories about companionship. Watching a good story about said companionship play before our very eyes reminds us of the warm and fuzzy sensation it induces. Because we want somebody to love and we need somebody to love us. And as soon as the end credits roll, we are hell-bent on finding that somebody to love.