How do you know when hes not interested?

When someone is not interested, they may exhibit certain behaviors such as avoiding eye contact, giving short or vague responses, not initiating conversations or making plans, and showing disinterest in your interests or activities. Additionally, they may not prioritize spending time with you or make excuses to avoid seeing you. Ultimately, communication is key in determining someone's level of interest, so paying attention to verbal and nonverbal cues is important in understanding their feelings towards you.