Input Wanted

Going to paint a quick scenario...would like honest opinions. You and your best friend, who could possibly end up being more have an agreement. You have sex with only each other. If the other were to have sex with someone, they tell you because you bareback each each other. One of these friends has sex three times over the corse of a month and never tells you. (they are doing it bareback) Meanwhile, he comes home and bare backs you as well. (you believe you are exclusive) As things get more serious and you're hoping to move toward a relationship, you find out that your best friend, who was exclusively having sex with you, had sex with one of their ex-F*@k buddies a few times a year ago. Then he lies about it. Ok- I know...end it there. But you love him, so you decide to work on it. He's only had sex with you for the past year, even though this ex-sex buddy tried to get him to do it a few months ago, but your best friend never did it. Now, it's two weeks after finding all this out (knowing the ex fuck buddy is always hitting up your best friend to get laid) Is it reasonable to expect that if your best friend really wants something with you, they would ask the ex-sex buddy to not contact them anymore and delete them from snap-chat and their phone and request that the ex-sex buddy do the same? You're best friend says they don't want to because they'll never act on it because it's exciting to have someone want them, so they'd rather keep the buddy around than alienate them. (keep in mind- they are ONLY fuck buddies, not friends)