They all have regrets.
Tony wishes he could've been the perfect son; he'll never accept that there is no such thing.
Steve wishes he could've saved Bucky and had the dance with Peggy; then he realizes that he was needed more in a different era.
Bruce wishes he never turned into it; he could've had so much.
Clint and Natasha wish they could admit their feelings; it's too hard, too much effort, and they're both afraid of what happens next.
Thor wishes he had his brother back.
Yes all my friends had regrets. I had regrets to. I'm pretty sure we all wished we could never grow up but I was a sweet nice girl when I was young and still fought for what's right some times I wish I could go back to that but I had seen too many deaths too many battles and I couldn't go back. But our regrets where what made us the avengers we had to avenge ourselves and we kept each other going that's what friends do.