Ya know-I think sometimes people really struggle with accepting that we are individuals. Yes-even if we are poly, we are still INDIVIDUALS.
GG and I don't do pda. We never really have. We do hold hands sometimes. We will peck a kiss on one anothers forehead if one of us is leaving.
But we really don't do pda. It's just not a part of OUR relationship.
On the other hand-it doesn't bother him to see me being affectionate with Maca.
Maca is VERY into PDA (always has been). He's a touchy/feely/kissy/huggy guy. However;he really can't handle seeing pda beyond hugs and a kiss between me and anyone else.
I don't really see any of those things changing and I don't think that they need to.
We do all live together, so we have a lot of time together. As the hinge, it's my job to pay attention to the needs of both of my partners and ensure that neither is being put in the position of extreme discomfort because of a lack of foresight by me.
We do bbq's and dinners and bday parties and family nights with the kids and we've even been known to go out just the three of us. But I make it a point of acting "the lady" in situations where they are together, and not being overly physically affectionate. Because it makes them uncomfortable.
I think your partner and your metamour need to realize that YOU are an individual and YOUR comforts need to be taken into consideration regarding how everyone acts in a group function before group functions are put on the table. But-that also means that you need to state your preferences clearly and concisely.
"Love As Thou Wilt"