I don't agree, all Riku wanted to do was get off the bloody island as made clear by Xehanort.
"To some this is a prison surrounded by water, this boy set out to be free from this prison"
and Kairi made clear that she didnt want to be with Riku
"Sora! Let's take the raft and go, just the two of us!"
And Riku made it clear that he didn't care for Kairi either by dismissing her so quickly.
"What? Where's Kairi?"
"Kairi is coming with us!"
Darkness pools around Riku etc. Holds his hand out to Sora and Sora alone
We then find out that Kairi isnt even near Riku, no she is beside the door that Riku himself opened. Some people believe that that Kairi in the cave was actually just her heart so i guess that would mean that Riku was the one that split her from her body? Yeah sounds like best friends.