What should I do? I feel like I'm being left behind but I can't tell anyone because I don't want them to feel guilty.
Have you spoken to someone about this feeling?
It's hard to talk about, people might not understand how it feels like when they don't feel the same way.
It's important to get these feelings off your chest so you won't feel this way. Holding this in will just cause more resentment.
Nah, I feel fine.
It's understandable that you might feel uncomfortable talking  about your feelings with your family and friends. However, talking with others may help you to realize that you are not alone with how you feel and everyone is on a different path in life.