hassle (noun): a troublesome situation; something troublesome that interrupts one's normal routine.
"I know it's a hassle to complete this form now, but Mr. Rogers
needs it in his office by the end of the day."
hard feelings: anger; animosity; bitter feelings.
A: "I'm sorry that Jim got the job instead of you."
B: "I have no hard feelings toward him; I know that he had stronger qualifications."
hard-headed: stubborn; inflexible; unwilling to change.
"I don't think Julie will change her mind. She's pretty hard-headed."
hassle (verb): annoy; bother; interrupt one's normal routine.
"If you'd stop hassling me, I might get this finished on time!"