4. "Monogamy is not a natural phenomenon."
Monogamy has nothing to do with what’s going on in reality. The problem is that your partner failed to be loyal to you personally. Now it’s up to you to decide what to do next. If both of you agree that monogamy isn’t natural and both you and your partner can have lovers, well, then congrats – you are a perfect couple. If polygamy is for him only, then run as fast as you can.
Do you feel like competing with others? Or are you good enough to be your partner’s one and only beloved? What is it others have you don’t? If you're ready to accept your boyfriend’s other girlfriends, be ready to see the doc and take tests for STDs. That doesn’t sound fun at all, does it?
How do you respond? “Being sidetracked with talks about how unnatural or natural monogamy is? No thanks but no. My opinion might be different. You've made your decision without asking for my views. Our relationship won’t work since I am monogamous.”