Welcome to the board!
You don't mention how long you have been together with your girlfriend.
You've presented the idea to her. If she's interested, she will eventually bring the topic back to you. What the FAQs are probably trying to convey is not to pester a partner about the topic. Sometimes people (male or female) don't get the hint that the other partner doesn't want to deal or talk about a subject so they brush the topic aside with a 'we'll talk about it another time'...this gives one partner hope and they may have the tendency (particuarly for such an exciting topic) to turn into a 6 year old going to Disney for the first time (are we there yet? no... are we there yet? no... are we there yet? NOOOOOO
).
I honestly hope you were paraphrasing when you said:
but I mentioned the idea that maybe in a few years when we'll have had the same sex for quite a while, it would be enhancing for our sexual life if we explored other possibilities. Because with that you are insinuating that you anticipate the sex/relationship to become so ho-hum that you want to look else where to get your kicks. I mean on one hand...it's wow...he still wants me to be around in a few years, so that's a good thing. OTOH, he thinks that everything will be just so-so...and that's just insulting.
You've presented the idea to her. If she's interested, she will eventually bring the topic back to you. What the FAQs are probably trying to convey is not to pester a partner about the topic. Sometimes people (male or female) don't get the hint that the other partner doesn't want to deal or talk about a subject so they brush the topic aside with a 'we'll talk about it another time'...this gives one partner hope and they may have the tendency (particuarly for such an exciting topic) to turn into a 6 year old going to Disney for the first time (are we there yet? no... are we there yet? no... are we there yet? NOOOOOO
).
On the positive side, she gave you a reason why...not just totally shutting you down. That was an opening she gave you...did you take it and ask what she was so scared of? Sure the idea is scary...is he going to leave me? Will he like the way someone else does xyz more than when I do xyz? Why is he mentioning this? Am I not enough? Those could be some of her concerns and/or many more.
Good luck!