Arnold Schwarzenegger's son was hit with cheating allegations after he was pictured getting cosy with a female friend while on vacation in Mexico earlier this month (Mar15).

He slammed the rumours on, writing, "Would never do anything against my GF (girlfriend)... Girls have guy friends and guys have friends that are girls..."

His girlfriend's father Billy Ray has now spoken out to defend Schwarzenegger, telling, "He had fun. He's a good boy," when quizzed about the rumours.

Schwarzenegger has been dating the Wrecking Ball hitmaker since last year (14).