Okay, so when the three of you were under the influence of NRE, you either allowed or encouraged a new love interest to move with you, and now that you are less "under the unfluence," you're not comfortable with it. Not the first time this sort of thing has happened, not even the first time recently. (I am thinking of the most recent chapter of HMA and Violet's ongoing story.)
How does someone move into a living arrangement "without realizing it"?
Did the three of you discuss the dynamics and boundaries of the arrangement? Are you clear in your own mind what you need and want? Have you communicated those needs and wants to your partners, clearly and directly? Do you have a clear picture of what your partners need and want, and have the three of you reached agreements and worked out strategies to see that each one's needs are met?
It sounds (to me, based on just what you've posted) like your triad moved too far, too fast. And now it's time to build a foundation under the house find yourself in. Doable, but easier said than done.
It's time to think things over, and then talk and talk and talk some more with your partners. Get clear on what each of you need and want, then make a plan to meet them.
It can be done. Good luck to y'all.