My girlfriend not being effectionate

Hi,well I am having a couple different problems with my girlfriend. My problem is that its been a month that I been with my girlfriend and we hardly ever pop kiss and I am always the one to go to her for one, she rarely ever tries to give me one and even when I am dropping her off at her house she just gets out of the car with out giving me a kiss. I take her to the gym everyday, we are rarely alone together spending boyfriend and girlfriend time and try to ask her if she wants to hang out after the gym and she always has an excuse and tells me she has to be home with her kid or needs to study, but it seems to be easier for her to make time with her friends but doesn't invite me because she says she needs time to be with her friends, she doesn't want to see me all the time because it can lead to problems and we should have space. I am so confuse I don't know what to do and I would come to her and talk about the issue that I need affection and why don't we kiss and if she likes me, and she says she will try to be affectionate with me and that she does like me but I feel like she's not doing much and sometimes I feel like maybe I am doing something wrong, I try to do everything in my power to get her to like me more. Then she always brings up when guys ask her out to places and that bothers me a little,and I know she talks to different guy friends on the phone and one of the guys she talks to she use to like a long time ago and he invites her to places a lot and I just wonder if she tells these guys she has a boyfriend and I know these guys just want one thing and she's an attractive girl and she says they are just friends and she's not going to do anything with them and doesn't like them and she acts all cool about it like its okay its just friends. She also calls me a lot but when we talk on the phone we always talk about something with her and she talks a lot about some girl she's having issues with or she talks about herself like she wants to improve her looks. I just wonder why did she get into a relationship with me? I wish I knew what's really going on in her mind, I don't think she's cheating on me, she hardly ever shows that she cares, all she does is call me a lot and go to the gym with me, if we won't boyfriend and girlfriend we would be great friends because we joke and laugh about a lot of things but as far as being a girlfriend she's not being affectionate at all, what do you think?