Hi, welcome, and congrats on articulating and owning your sexual and relationship desires!
Sounds like you are a submissive and want your man to be your Dominant. You want him to have a primary female partner, and to serve them both, perhaps co-Dom you.
Welcome to the world of BDSM. You can be poly and kinky. This board is great for learning poly relationship skills. However, if you want to learn more about Dom/sub, Master/slave lifestyles, try the website called Fetlife. It's like Facebook for kinky people, and there are many online groups there you can join to read or ask questions of experienced Doms, Dommes, subs and slaves. It can also link you up to "munches" (non-sexual meet and greets for kinksters for socializing) so you can meet people like you in your area. I know you're both introverted, lots of Masters and slaves are, but if you want your Sir to find a gf, you'll need to get out there.
Good luck on your quest for fulfillment.
Love withers under constraint; its very essence is liberty. It is compatible neither with envy, jealousy or fear. It is there most pure, perfect and unlimited when its votaries live in confidence, equality and unreserve. -- Shelley
Mags (poly, F, 60) loving miss pixi (poly, F, 38) since January 2009, living together since 2013
also loving Punk (monogamish, former swinger, 42, M) since Oct 2015
"Master," (mono, 34), miss pixi's Dom for 2 years