I'll be frank here, people do not show affection to shame, ridicule or make anyone uncomfortable in almost all cases, meaning sure there may be a very rare couple that actually thinks this way but as a norm or average they do it because they enjoy that they are in the relationship they are in, they are proud of it and show it publicly because honestly they don't care how you think or feel about "PDA" I know no one that ever got in a relationship to score points in high school, college or anywhere, but connected with someone because it's what they wanted.

Society, honestly is not imposing any rules on you, but internally you feel that it is, this is a fabricated idea. You can say you feel that you're pressured by friends but without context and actual events telling me how people pressure you to be involved with someone, it's hard to analyze.

Can you explain your perspective on why you think that in Uni/College that you are "expected" and or pressured to be in a relationship or is it just that many people are and you feel that you don't fit in because you are single?

Be happy and at peace with yourself and your situation. Likely others are ambivalent or indifferent to what your situation is for the most part. Strangers for the most part are oblivious to how their behavior is affecting you. try to recognize that people that are in relationships that are good and working are going to be happy with it and display this wherever they are. I know I would if I was with a woman I loved and out in public. As a typical guy, I like people to know "this is my lady" when I'm out and about and it's not ever about making others feel small, out of place or shamed. It's just about displaying that "hey I'm here, this is my woman and I'm happy"