Mental weakness

Hearing the voice caused Gabby and Billy to turn simultaneously. Since the sunlight shone on them, they couldn't help but squint their eyes. Once their sight became clear, they saw Coach Henri walking towards them. 

"Sir," Gabby greeted.

Billy quickly released his grip on Gabby's wrist. He put his hands behind his back while lowering his head. He looked like a mouse meeting a cat.

Once Coach Henri was standing next to Gabby, he immediately grabbed his student's hand. He then glared at Billy while standing in front of Gabby.

"Don't you dare do something indecent with my beloved student!" Coach Henri folded his arms. "If I see you touch Gabby again, I'll make sure I'll break your hands,"

Was this Coach Henri actually Gabby's trainer or boyfriend?

"Sir," Billy rubbed his nape. "I can't possibly do that. I'm Gabby's old friend. Can't I just talk to her for a bit?"

"Oh, really?" Coach Henri asked.