Hey Sadatul,
Proof of relationship - 40 Wedding/Honeymoon/Family pictures, Chat logs, Phone bills, FB Mgs, Honeymoon ticket/hotel booking, Other trips ticket/hotel booking, Copy of passport pages with Visa showing traveling together (same day exit/entry stamp, consecutive Visa number).
But do you need to prove your relationship again to CIC - Singapore? I thought CIC-M approved me as a sponsor after scrutinizing proof of relationship.