consider cheating?

Not telling and telling different from the truth...

Consider in a relationship.. when the guy did something ,he didnt tell the girl.. but when the girl ask the guy will tell the truth.. is this still consider cheating?
i think is not.. not telling and telling different from the truth is two different thing..

i did something very worng yesterday.. i shouldnt have did it.. i cant forgive myself.. and i fell so sorry for her.. i was so emo all night.. till that i ask her for forgiveness..im fell better now.. im happi that she will forgive and understand what i had did.. but i cant forgive myself.. and so sorry to all my fren that had worry about that morning...