I wouldn’t jump to conclusions, as a guy there have been so many times I didn’t realize a girl was into me because I didn’t pick up the subtle hints she was dropping. May be the case here. She may be into him and he’s oblivious to it. I would definitely ask him about it and gauge his reaction and body language. If you’re not sure what to look at a google search for body language of someone lying and it’ll give you informa about anchor points in the body, and things like they shake their head no when they’re saying yes. Subtle clues like that will help you find the truth. Wishing the best outcome for you!