I think we all should give Arjun the benefit of a doubt. I think basically he is a decent chap but he allowed his feelings for Ovi (which is more brotherly) and the guilt he felt for letting Ovi down, to overcome his love and loyalty to Purvi. He is not correct but i shall give him thebenefit of a doubt. Also Purvi was no easy person to mollify, Arjun is never certain where he stands at any point in time with Purvi because she is always jumping the gun.
I think when all stakes are down, Arjun will not be afraid to speak up and will not be afraid to do the right thing - and that is to support one he loves - Purvi. After all the relationship is two-sided - both he and Purvi love each other and both should stand together and take th blows that will come. And the blows will come.
When that happens I hope Purvi will not become an Archana-wannabe and go all mahaan and offer to sacrifice their love just to molllify Ovi.
I hope Purvi will stand with Arjun and that both will not be afraid to say "Yes we love each other" Arjun should also inform the people that Purvi was never aware of Ovi and thequestion never arose because the love just happened - it was not a case of one pursuing hte other to win the love. THEY JUST FELL IN LOVE that's it full stop.
LOVE HAPPENS... HEARTS BREAK... that is the reality of life.