Friends' PDAs, versus mother's discomfort. Who is right?

[LifeOnPluto]

Just to throw in another opinion... I don't think PDA always means a couple is showing off. If it's a new couple, especially if one or both haven't dated much, just being able to rest your head on someone's shoulder or rub their knee might seem so wonderful and novel, because you've rarely had a person to do that with, that it's hard to stop whenever you're together. It's hard to be aware of yourself around others/in public when you're still reveling in the feeling of having someone to do this with. At least, I think this is true for some people. It doesn't make the outcome less annoying; but again, I like to think about the why, as it helps me figure out what to do about it.

I remember, long ago, when my friend Amy had her first serious boyfriend. Fortunately he lived far away so we didn't have the PDA aspect, but she talked about him all. The. Time. I would say 95% of the things she said involved him somehow. Seriously. Anything anyone else said would remind her of something about this guy. "Wow, the weather is nice today." "Oh, Joe was just telling me how bad the weather was in his city..." "Pass the salt, please." "You know, Joe is on this low-salt diet..." And a lot of it was about how wonderful and perfect and amazing Joe was, and how he thought she was wonderful and perfect and amazing. "I talked to Joe for three hours last night and he said I was so smart and funny, and he couldn't wait to see what our children looked like, he hoped they had curly hair like me..." [Where's the "disgusted" face?] Nor did she change her behavior even after increasingly pointed comments from the rest of us. This lasted for the entire six months of their relationship, until she flew out to see Joe special and he dumped her and started dating someone else two days later.  She did learn from it, though, and didn't act that way about any future boyfriends, even the guy she's now married to.

The bolded is very insightful and I think a major reason for Zoe and Zac's PDAs.

It could also partly be the need for reassurance, as a PP suggested. I know they are both currently figuring out their boundaries as a couple. For example, Zoe told me that in the earlier months of the relationship, she got upset when Zac would do things with his (male) buddies, but not invite her along, but she's reached the point where she's realised it's ok for them to spend time apart every so often. 

[TurtleDove]

I don't engage in over the top PDA, but I am 39 and my BF is 47 (dating 1.5 years) and at our lunch with his parents and kids today we would randomly touch each other, not because we were insecure or needing to mark territory, but because we love each other and it just kinda happens.  I think some people are simply more touchy feely than others maybe?  And like I said, my parents do the same thing.  My sister and her husband (married almost 14 years) do too.  It's good to see, in my opinion, for kids too.

[MyFamily]

- A couple of times, Zoe and Zac disengaged from the main conversion, and had a brief (lasting only seconds), whispered conversation of their own, which ended with Zoe giving Zac a quick, soft, kiss on the lips.

This is what would bother me. They disengaged from the main conversation and had a private conversation that did not allow for anyone else present to be a part of; that is rude to me.  We had some friends who did this, and it reached the point my dh did not want to interact with them.  It has been probably around 7 years, but even now, after they married, divorced, she's remarried and had a child, my dh still doesn't want to be around her (I refuse to have anything to do with her ex because he abused her).  Their interactions and just stepping back from the conversation like that was rude.  And I'd say the same thing if two people who weren't a couple did the same thing.  It is one thing to have a side conversation at a party that would easily allow others to participate if they wanted to discuss that subject, but the type of conversation they were having doesn't allow for that; and even if it was short, that feels rude to me.