Well .. I'm really sorry that every day you guys find the Kumkum story & characters either crap or boring or gone case .. or whatever. But .. what to do .. a story is a story .. and all these actors are playing their part as they are said to. Secondly .. creatives are working (like I've mentioned earlier) around many factors .. which, kinda makes it impossible to please everyone .. all the time!
As far as Sumit is concerned .. well, yeah . Aditi asked him to leave .. and he did not! Simply coz he believes in supporting someone whom he considers his friend .. and also, he's a nice guy .. not very selfish and keeps others' happiness before himself. Ab woh hai hi aisa .. and thats why we love him so much!
Up until now, Sumit thinks of Ranveer as the one who has ruined Aditi's life (in the name of love). I'm sure Sumit will realise its not like that. Now .. according to the track .. its quite obvious that Sumit will realise that Ranveer does love Aditi and hence will play cupid and get them together.