Well, there does seem to be a lot of monogamous people on this forum who have fallen in love with polyamorous people. So a slightly amended advise is not to fall in love with someone who can not accept your lifestyle.
But that is hard. You love who you love. I don't think we ever plan to fall in love. We either guard our emotions so we don't chance exposing them or we expose them and feel what we feel. There are pros and cons to both approaches.
Sorry it doesn;t sounds like it will go any further. However, maybe you can consolidate yourself with the idea that you can share part of her life in a limited capacity. (Yeah, small consolidation.)