Thanks all for the comments!
YouAreHere, thanks for the empathy. I think i relate to you A LOT. That is basically how I feel. I just don't want to be the subject of someones conversation on the ride home I guess. I know it sounds weird, and I shouldn't care what others think but I do. Actually talked to my GF today and she seems to understand my behavior a lot better too. I'm just not very comfortable being all lovey dovey amongst people I don't know very well-- simple as that. Amongst very close friends that understand our relationship, I don't have as much of an issue.
She is definitely not forcing me to be more publicly affectionate, but i guess recently it has been bugging her, and i haven't really told her why i don't like PDAing till today.
Vanquish: Yeah we're equal. I guess he's just more forward than I am. You know, like the first to extend his hand out for her to hold. I wouldn't mind PDAing, I'm not at all opposed to PDAing. I don't necessarily have urges to do it. It's just that if he starts doing it with her first I'm one to back off for the rest of the outing. If i started doing it and he would back off like i do then maybe i would be more comfortable with it, but that doesn't really happen so idk.
There are other issues that we need to work out, but at least i feel as though there is some consensus that not PDAing with my GF in public when we are all together is not necessarily uncommon and that she really has to understand how i feel more so than i need to change.
Thanks for the comments. Very much appreciated. I'll probably post so more issues i'm grappling with later on this week. Being in a poly relationship is work!