I'm sorry if I'm not what you bargained for.
I'm sorry I tricked you into thinking I was what you wanted.
I'm sorry it took so long for me to show who "I am." (or at least try)
I'm sorry if I'm annoying.
I'm sorry if me changing so much drives you crazy.
I'm sorry I never keep my promises.
I'm sorry I can't keep your trust.
I'm sorry I don't trust you.
I'm sorry you never asked me to bring this on you.
I'm sorry I'm not trying hard enough.
I'm sorry we can't get along.
I'm sorry I don't tell you I love you enough.
I'm sorry I don't appreciate you enough.
I'm sorry I won't give you a break.
I'm sorry I'm not the best influence.
I'm sorry I lied to you.