When women emphasize "BOYFRIEND" without you even saying anything....

I'm sure I'm not the only one this has happened to.    I'll give two examples....

1. I was talking to a race car driver at my local racetrack about, well, racing stuff when she just had to mention about something about "my boyfriend" and clearly emphasizing it before going right back to, well, racing stuff and her car, etc.

2. I was in Publix and I entered one of the isles to get something when I saw one of the female workers talking to one of her colleagues and I just glanced at her, and she made a point to say "my boyfriend" loud enough to where I could hear it clearly.

Now, I get that it's a defense mechanism.  When a woman says "my boyfriend" out of the blue without you even inquiring if she has one (or really have no intention of asking her out) and makes a point to emphasize it, it is code for "I'm not into you so don't even think about asking."

I get it.  Women have to have some ways to tell men to back off.   But do they really have to activate a defense mechanism every time a man comes near them?  

There are some times when women activate a defense mechanism - like mentioning a boyfriend out of the blue - and it is just silly when it's in a certain situation or environment when the chance of a man trying to hit on them is very low due to common sense reasons.

Let's take the two examples I mentioned:

1. If I were to ask her for her digits I might be kicked out of the racetrack and possibly even banned.  I like going to this track and that would be pretty bad to be barred from going there just because I wanted to be brave.

2. The woman in Publix is probably hit on quite a lot.  The odds are very high and it's not in my favor.  Plus it's kind of awkward when if you do ask her out, get turned down and later on find yourself in her checkout lane. 

So really, is there any reason for a woman to "arm herself" when guys around her know it's not a good idea to try to hit on her, like the reasons stated above?  

Now I'm sure people, especially women will be like, "But Sam you're not a woman, as a woman you always have to be prepared to be hit on by guys no matter where you are."

Sorry, but in my viewpoint.... NO.  Most guys are smart enough to weigh the risk Vs reward when even thinking of approaching a woman in hopes of getting her number.   If the reward is very small, but the risk - say, the possibility of being banned from a place - is big, he is not going to do it no matter how pretty he thinks a woman is.  

So in other words, if you're a woman.... you don't have to raise your defense mechanisms like saying "My boyfriend" all the time.  It will just make you look silly in situations like the examples I described above.