I'm a 24 year-old male that has just worked for 3 months in this new job. Sitting next to me a is woman who is 4 years older than I. We have a normal colleague relationship (at least I think it's normal, you know, the usual small talks here and there, going out for a drink together with other co-workers once or twice a month).
She just got her hair cut last weekend and on Monday I jokingly told her, "That new haircut makes your face look bigger." She didn't say anything and I just laughed it away. However, today my manager called me and told me that it may have been quite rude to say that to her (it was only she and I when I commented about her haircut by the way) and it may be considered as harassment. In retrospect, I think he's right. We are not that close yet so I may have overstepped a bit.
I did talk to her directly and apologized but interaction between us still feels awkward. How can I improve this situation?