The most common allegory I have come across to help others wrap their mind around the concept is comparing loving more than one to the love parents got for their children. That when there is one child already and a second one is born, the first doesn't suffer the sudden absence of love from his parents or one of the partners the absence of romantic love from the respective spouse. They are able (normally) to love both. Same with the third child and the fourth and so on. Romantic love is a different concept from the love you feel for your children, but she may see the link for the possibility to care deeply for more than one person without dimmishing the feelings for the others you care for in your life.
I had a hard time trying to explain to my two mono men what was going on in my head and heart. They haven't been able to fully understand what I was talking about up to today. But they don't need to as well. We agreed to a simpler conclusion: They let me show it to them. I was able to just show my feelings and they both were able to see that it just is the way it is. My husband would have said something, if he would have felt less loved than before. My boyfriend would have said something, if he would have felt less loved than he needs to be and both knew how this feels like from other relationships. And when we just tried, all involved recognized that it was working.
MY advice would be: Try to help her wrapping her mind around the concept theoretically will help, but at some point, if she is really mono, she just can't understand what you are talking about. Good luck with figuring it out with her.
Facts: 30, female, bi, v-type relationship with Sward (husband, straight, mono) and Lin (boyfriend, straight, mono), poly-fi and co-primary.
Last edited by Phy; 12-22-2011 at 06:54 AM.