It's very easy to blurr the line between self respect and ego. Shravu's self respect is masked as his ego. Both of them are going back and forth between being egotistical and being respectful of themselves. So it's very hard to say if their actions are rooted in ego or do they stem from self respect.
As far as you questions go Sami I think:
Self- respect is when you respect yourself enough to stand up for yourself. It doesn't have to be standing up for yourself just to prove a point but to understand you have self worth.
Ego for me is being boastful, and undermining the worth of other people, while putting yourself up on a pedestal, and exuding superiority it terms of self esteem over the self esteem of others.
In the context of the show: Sharavn is respecting himself, he is respecting his feelings, his emotions by creating distance between himself and Sumo. His actions stem from both his self respect, and his ego. The problem is when you start respecting yourself too much, and giving weight to only your problems, your pain, self respect can turn into ego. This is exactly what happens to them both.
Shravan is drowning in his own pain. He hasn't been able to let go of it. So naturally specially with regards to Suman, he is reminded of the time when she had insulted him. And when he remembers all that, he is reminded of how worthless he had felt or rather how worthless he was made to feel. Because of this, he always tries to show her he doesn't care, he doesn't give a shit about her. So in the process of allowing himself to protect his self respect, in his efforts to not look weak, he turns egotistical. In simpler words it's a defence mechanism for him.
Suman is drowning in guilt and remorse. She did something she shouldn't have done. And those 10 years and separation from Shravu made her realize her mistake. But now that he is back and he is showing her attitude, her sense of self respect has also gone up. She knows what she did, and she apologized for it. But he still acted nonchalantly.
They don't want to present themselves as weak in front of another, and by doing so they end up acting in a way that seems too selfish and too egotistical
I am sorry if this doesn't make sense at all. I swear it made sense in my head.