Here is a list of some masculine traits:

being aggressive
being independent
not being overly emotional
being objective
being dominant
being active
being competitive
being logical
being direct
knowing the ways of the world
being adventurous
making decisions easily
never crying
acting as a leader
being self-confident
being ambitious

These are traits that taken together project “maleness”. Just as we guys are attracted to feminine traits in a woman, women are attracted to masculine traits in a guy. So when a woman tells you that you are too nice, she’s really saying that you’re not projecting enough masculine traits to interest her. The other thing about being too nice and overly compliant, is that she may think that there’s something not quite right with you. That you’re too easy or perhaps desperate to get a girlfriend. This diminishes your “worth” to her.

Don’t let the list overwhelm you because you don’t have too project all of them to a high degree. You want to be “who you are” yet be attractive as a man. Choose the ones that you already have and don’t suppress them when you’re with a lady. However, being confident is one of the more important traits that you should put some extra focus on. Any one of the above traits if over done or not done in a natural way can make a person seem like a jerk.