Know that you are awesome, independent of anyone she might like more.Accept that she might find someone who suits her better. Don’t try to buoy your self-worth by placing it in her hands and then defending it from other suitors. You are worthwhile not because any girl likes you, but because you are living a good life (you are living a good life, right? You’ve probably never gotten this real with people. There are too many wonderful, beautiful people for me to shut any doors.
Decide and manage the cadence of your relationship.
A few general guidelines: Just hookups – Only contact her when you have something of importance to say or are planning to see her.
Plan on seeing her no more than once a week and usually only at night/the following morning. But you need to be damn clear that things ARE NOT exclusive and they ARE NOT moving towards exclusivity.
Tell her you like that things are casual between the two of you and that you are happy there is no boyfriend/girlfriend expectation. A lot of girls think that after a period of time in an open relationship, you’ll come around. A girl can be crazy about you, but if her friends make her feel like shit for seeing you, you’re done.
There is nothing wrong with monogamy, assuming that’s what you want.