It could be because she actually has a boyfriend.
If you approached this girl and she told you that she has a boyfriend, she may honestly have a boyfriend.
Lots of girls have boyfriends.
She may be one of them.
You can’t simply assume that every girl that you talk to or approach is going to be single.
There are going to be lots of girls that you approach that already have boyfriends.
Your mistake is to continually dwell on those girls that tell you that they have a boyfriend.
This is where you have been failing.
It doesn’t honestly matter if the girl is telling the truth or not.
Either way, she is conveying the message that she is not available.
Some guys tend to make the mistake of misreading what she is saying.
They may believe that she is only saying this just so that she can play hard to get.
This is unlikely.
She has conveyed the message that she is not interested.
She may not be interested due to the fact that she has a boyfriend.
She may not be interested due to the fact that she just doesn’t like you.
Either way, simply accept that and move on to other girls.
When you continue to question her reasoning, you are only making it that much harder to move on.
You would be wasting so much time on this one girl who has told you that she has a boyfriend and ignoring the several other girls who may be truly interested.
Don’t take it to heart when a girl tells you this.
Stop taking things so personally.
She has her reasons why she told you what she did even if she was being untruthful.
Your task is not to start trying to figure her out.
That is not your job and quite frankly it can be mentally exhausting.
It will preoccupy your time in such an unproductive way.
You would begin to focus on something that gives you no benefit.
The more you keep asking yourself why she told you that she has a boyfriend, the more you will doubt yourself and question your appeal.
You may believe that she lied.
You may believe that she is actually single. However, does it really matter at this point?
She is conveying the message to you that she isn’t interested.
Whether she has a boyfriend or not is not really relevant.
The message that she is conveying is relevant.
Perhaps you have known this girl for a while and feel like you know everything there is to know about this girl.
Hence, you believe that you know how she thinks. You may even have mutual friends.
Perhaps the mutual friends tell you things about her that makes you feel even more so that she likes you and is merely playing some kind of game.
Even if she was playing some kind of game, she would be very difficult to read.
If you were to pursue her further, you would only keep encountering even more games.
At what point would those games actually stop?
That wouldn’t be your call, it would be hers.
She may never make that call because she would rather lead you on.
Is that what you want?
Of course not.
Leave this one.
Move on to other girls who are single and available. They are out there.