You're asking your partner to believe, in the face of overwhelming social messages to the contrary, that you're not looking to replace him; that the reason you're open to other partners is not because there's something wrong with him; that you're not asking for permission to cheat; and that you don't have one foot out the door. That's a lot to deal with. You're asking your partner to accept that having other lovers isn't just a way for you to move from one relationship to the next. Make sure that's true. Make sure you are worthy of that trust.