I never felt any social pressure during either of the relationships I mentioned above. People may have expressed an opinion here or there...and there was that one awkward, "....and this is your....daughter...?" moment. But I typically take outside opinions with a huge grain of salt and a healthy dose of "you have a right to have an opinion -even on stuff that is none of your business- and I have an equal and opposite right to ignore your opinion." I figure as long as I'm not intentionally harming someone or their stuff, I'm most likely ok.
I seem to be quite deficient in whatever it is that makes people care what others think about them. I was pretty low on that to start with....and what little I had has decreased as I've gotten older. Judge me, my actions and choices all you like, chances are real good I'll be totally oblivious to that judgment, and on those odd occasions where I become aware of it, I usually decide it's not important and continue with what I feel is best for me.
I think individuals who do care what others think about them or who are concerned about things like pleasing their family probably aren't going to find themselves in age gap relationships - or any other type of relationship that may create waves (different religion, different race, etc.) at all....if they do, they won't be there for long.
But not everyone is concerned with what others think.