In general, not being aware leads to some 'stupid' actions.
What does 'being aware' mean? It means having something (the thing you are being aware of) in mind.
For example, someone who disregards what their girlfriend/boyfriend feels, doesn't have in mind what it is that the other person may feel. The most observant would even say, they didn't put themselves in the shoes of the other person.
This indicates their lack of awareness. When they do something that would seem obviously immoral or incorrect to an outside observer, they simply don't realise that what they're doing is causing harm. One must add that although the offender may not see that he is causing harm, the offended knows for sure that they have been unfairly treated.
However, this does not excuse the behavior. Why? Because external decisions about being precautionary before engaging in their behavior could have prevented a transgression from taking place at all. In essence, being more aware reduces 'stupidity' in general.
To not extend myself more than I already have, I'll be brief with the conclusion:
All could and should strive to be more precautionary before engaging in behavior with other people, such as by asking "Hey, is x okay?".
And as we make clear our boundaries to people in our lives, they won't commit a lot of mistakes, unless they are deliberately malicious. Those two steps make us more aware, and lead to less 'stupidity' overall.