If you are finding it difficult to forgive anyone who offends you, it implies that you are suffering from the complex of inferiority because, the forgiver is always superior to the offender.
Forgiveness is an act of showing one's superiority over an offence / offender, So if you can't forgive, it simply shows that you are no way better than the offender.

If you are finding it difficult to ask for forgiveness from anyone you 've / might have offended, it implies that you are suffering from the complex of Immaturity because, only the matured have the boldness / courage to approach anyone they offend and ask for forgiveness.
Some say that pride is what makes it hard to ask for forgiveness but the truth is, Pride is a manifestation of immaturity.
Asking for forgiveness is a way of showing your maturity.
What is so hard in "am sorry, forgive me"?.