Have to agree that Swara always keeps her sister before Laksh, she cares for him, considers him a true friend from her past but would she have gone beyond her comfort zone to attain him, if Ragini hadn't done her suicide drama? Not sure.
With Sanskar it's entirely different. She trusts him, Relies on him completely. Like Helly said in one of her IV, Sanskar has become like an addiction to Swara, without which she cannot possibly live. Sanskar wishes to give away everything even Swara herself for her own happiness, which wasn't the same with Lakshya's love, it was weak, though he trusted her during the drugging drama, but he failed badly on the marriage day, he chose to believe the video, IMO which is also understandable..., but deciding to marry Ragini was absurdity. His love lost to Ragini's plotting.., which I'm sure wouldn't be the case with SwaSan! Sanskar trusts Swara and loves her unconditionally! His anger came out only when she failed to trust him the way he expected to., even in that Swara's trust only Wavered but Sanskar's trust probably hasn't! SwaSan have a long way to go before they can become an actual couple, since their path is full of hurdles, but hope to see them triumphing everything with flying colours.