The idea of unleashing your deepest desires to someone you have been close to over a long period of time; raises doubts about - would they embrace or would they be apprehensive to your fantasies.
Before expecting her to answer you in a simple yes or no, I believe you should introduce her to the idea. Use a third person example to see her response.
If I were you, (me and my partner being sapiosexuals) I would start off by mere facts. The reason why you would enjoy watching another man with your woman has a very strong linkage to your (or most men's) sexual instincts.
Studies state that men produce higher amount of testosterone when mastrubating to porn with two or more men with one woman; than when watching a man and woman having intercourse. Again, if I were you, I would share this with my partner and would establish a base to my fantasy. The whole while, I would strongly recommend - Do not expect her to agree or disagree. Just go with the flow.
By being creative, trying new things... Being more candid and open about asking what I like or telling me what he would like me to do.
And I've noticed, with time, foreplay sort of fades off. I would like to keep the intimacy alive with the foreplay. Lots of it.
I've always been a little shy and introvert-ish. I squirt almost every time I masturbate, but never during sex. Mostly because either the guys weren't doing it right and also because I wasn't very comfortable. Until, only after reaching a certain level of comfort in a recent relationship, he did make me squirt. While having sex in the classic missionary, I was nearing an orgasm and somehow, he might have felt my pussy squeezing his cock with the pressure... however, he gave a few hard thrusts and pulled out. And there it was, gushing out like love. It went on for at least 10-20 seconds, and before I could wrap my head around what was happening, I instantly looked at him, hoping to find some approval. His eyes went wide with amazement... It was as if he had found a new function to one of his gyzmo's! He made me cum several times after that, making sure I squirt each time. When we finished I felt drained to the core, unlike the bed which was drenched.
Of course after that episode I was banned from squirting anywhere around the bed! :P
If you are 16-18 and are attracted to a 20 to 30 year old woman, its natural. She's at the peak of her sexuality. When a man is in his 30-50, and is attracted to a 16-20 year old, she'd be at the peak of her fertility. So either way, its natural. However it doesn't have to happen with every guy, since some men determine fertility and sexuality not by a woman's age but by other factors.
You know you should through out your fuck doll when, your lover is really quiet during sex and you're enjoying it!
I don't scream. But yes, there's a gratification - from audibly loud breaths to soft moans to louder moans... depends on how hard I'm being fucked! ;)
One night when I was fooling around with my lover in my dark university room with my room mate, ignorant and fast asleep, I was threatened that if I made the slightest sound, even if it were a tiny little squeal, he'll stop fucking me and leave that very second. I was obedient. But it was awkward. He then realised how important my moans were to make him cum! ;)