She may have a boyfriend.
However, it isn’t likely that she cares that much about her boyfriend or sees her relationship with that boyfriend lasting that much longer.
If she made the first move on you and she is now saying that she has a boyfriend, she may have been trying to gauge your chemistry together and later discovered that it just wasn’t there.
At this point, she may have realized that she didn’t want to take her interaction with you any further, so she told you that she had a boyfriend.
Again, she may indeed have a boyfriend.
However, she may be looking to get out of that relationship.
She may have seen you as a prospective new date or boyfriend.
Your interaction with her may not have gone according to how she hoped it would go.
There may have been a lack of commonality or she may have found something about your demeanor or life unsettling.
This may have caused her to stop and realize that you aren’t the one she would want to be with next.
Another reason why she may have made the first move and then told you that she has a boyfriend may also be because she is playing a game with you.
She may actually want you to be the one who chases her.
She may want you to show her just how much you like her and how far you are willing to take this.
By telling you that she has a boyfriend, she has tried to plant the seed of competition in your mind.
Just how far are you going to go to try to get her?
This may be a girl who thrives on being the one who is chased.
In either one of these scenarios that I have just described, she may indeed have a boyfriend but she is clearly not serious about him.
A girl will often act this way when she is looking for an out from her relationship.
She may not want to get out of the relationship quite yet, not until she has actually found another guy to replace her boyfriend.
This may be the kind of girl who is used to being in relationships and is rarely single.
Thereby, she will rarely have a period of transition between boyfriends.
She will basically move from one boyfriend straight into another.
A girl like this can typically be quite demanding.
She may be all about being in a relationship at first but can get easily bored.
Thereby, her relationships often may not last very long.
One of the most effective ways to tell if she was telling you the truth when she told you that she has a boyfriend is in observing her social behavior.
If she spends a majority of her time hanging out with her friends or work colleagues, it is unlikely she has a boyfriend.
If she had a true boyfriend, she would be spending a good chunk of her time with him.