#4 You never meet his friends. If you’re romantically involved with someone and the feelings are real, you meet each other’s friends. You get involved in one another’s lives. And if the guy you’re seeing isn’t doing that, he’s playing you.
Never meeting his friends just shows you that his friends might not even know about you. If he’s not telling his friends about you, does he truly have feelings for you? Probably not. Which means he’s just using you for something else entirely.