how do you deal with a problem , that problem with me being the fact that when ever i approach a girl they are almost always seing someone , how do you deal with that??

Depending on how they say it I go with either one or two ways at it.

1: Ignore it like I never heard her say it and just continue with the interaction and the pickup like I would normally.

2: Smile really big and touch her arm playfully and say, "Oh you thought I was trying to pick you up?
That's kinda cute (smile big and look like you are waiting for an answer for a sec and then before she can reply,)
I figured by the way you looked that you would be fun, and I always enjoy adding new people to my social circle"

Keep a big smile and almost like you feel embarrassed look for her that she suggested that you where picking up on her.
This will force her approach to change and give you time to redirect her.
A lot of women use the I have a boyfriend line to weed out regular men from the men that are brave enough to proceed, (Alpha's.)
This is a standard shit test. After that just use what you would normally use to number close.