Ever looked at a kid and see his/her innocence? How they express themselves?At a young age, without thought or comprehension, they say I'm sorry, or I Love you to you because they know you have showered your love on them.
As they grow older and come into a relationship, they tend not to express that much because of the fear of affecting the other person's feelings and find it very 'EEEeee' to say it...

As much as Men like me hate to admit, we to an extent are also emotional beings..The thing the prevents us from saying it out or expressing it is- E.G.O...I've realized that generally, men like me want women to pamper and show their affections to us but not want to admit it openly...All you need to do is swallow your big ass ego and say I'm sorry, i love you and you'll turn her storm into calm seas.