When Gael exited the hotel earlier, Giovanni offered to go for a drink, but he declined. He didn't have to say it for his uncle to know that he wanted to follow Angela and make sure she gets home safe. So Giovanni gave him the keys to the SUV, then he left in another vehicle with his men.
Like the stalker he was, he tailed the Town Car as it headed towards Angela's apartment and parked across the street when it pulled up in front of the building. He sat in a long silence as he watched Angela and William get out of the car, and the bitter part of him thought she'd invite him upstairs—which was not what he wanted, but at this point, what could he do? Thankfully, she didn't. But the asshole put his arms around her.
Gael jerked up in his seat, itching to rip William off her. Good thing the hug didn't last that long. He didn't like the man. William and his cousin, Damien, were both sly. Quite hypocritical for him to think that way, but whatever.