He was in a toxic relationship with your best friend, and you didn't know about it. He didn't want to say anything, not wanting to ruin your relationship with her.

But.. these past days.. he's been focusing on you lately...

Kurama doesn't know anything about you.. other than that, your ex-boyfriend was killed by a car only 2 months ago. The whole school knew and constantly made rumors like 'She probably killed him with her car'.. he hated those..