Because Sree once again is drifting towards KV/Dipika and now Shiv is threatened (rightfully so). Rohit doesn't trust Sree (again, rightfully so; he is basically a scapegoat for Sree).
So they join with HC since they have more members and also since these two don't really bond well with Megha/Dipika/KV. Without Sree there isn't that "glue" for them to strategize together.
Jasleen didn't seem to be making any strategies with anyone.
But in the end, Shiv/Rohit did team up against HC, saying they will eliminate them to secure a place for themselves because they didn't trust Romil to take Surbhi out of captaincy race. So they did form an alliance against them but then KV came and knocked Rohit out (I don't know why).