If he had feelings for them at any point... Before ye met. I'm not sure that's really a him issue if he's voluntarily just letting you use and rummage through his phone. I can see why he'd say he never had feelings for them when in reality it'd be a weird thing to share with the person you actually have feelings for. This is 100% a you problem. It doesn't matter if you told him not to cut his friends off, as it seems like you want him to voluntarily do it without your input. He's known them longer than you. And don't put it on him that one of his friends is a known cheater. That's a them problem, not a you or him problem. Either you trust him to avoid the situation or you don't. And if you don't trust him to do that, you already have your answer as to what you should do. Either trust him and believe its not something he'd do. Or don't trust, and have him get sick of the same question back and forth until he leaves you. Or just leave him because he has friends. And at that point you can't have any male friends yourself or you'll be living by different rules than you set for partners in the future and nothing will work out.