Seeing Reino, made Bram remember the man he saw in the CCTV footage of Clara's bedroom at that time. He even tried to play the recorded video back which he didn't fully see at the time because he got carried away with emotions and rushed to Clara's apartment.
That night the man he saw on the CCTV footage of Clara's bedroom approached Clara and even landed a kiss on Clara's head. Bram's emotions peaked when he realized that the figure of the man who hugged Clara and the one on the CCTV was the same. Moreover, seeing Reino and Clara's meeting last night, it was clear in the photo, there was a date when the photo was taken, making Bram think that Clara often met Reino secretly, and he don't know what they were doing without Bram knowing. Bram's mind immediately raced, especially after Bram found out that the man was Clara's ex-lover.
Don't ask how he knows. Money made it easy to get whatever information he needed.