Why does my female friend keep telling me “If I got a boyfriend I would stop talking to you”?

[Anonymous]

I know what she’s trying to say but the question is why? She’s a friend that I talk frequently. We’re just friends and I don’t have feelings for her. I’m not even attracted to her. And she knows this. But she’s said that to me multiple times, like she really wants me to know that and wants to keep making sure that I know that and then double check and then triple check just to make sure. She wants to hammer it into my head so I know that she would stop talking to me if she got a boyfriend. But why does she keep bringing this up to me? Does this imply that if she in a relationship with someone else she’ll not want to be around me because she doesn’t trust me around her or because she doesn’t trust herself around me? You could point out that she would do that because he wouldn’t like me in the picture for obvious reasons. But she DOESN’T have a boyfriend. She makes jokes to me about having a boyfriend because that idea is absurd to her. She goes on rants about how much of a “femcel” she is and about being a virgin, etc. one time I asked her if she had a boyfriend and she just laughed at me and called me stupid. I’ve narrowed it down to 3 possible conclusions: 1. She has feelings for me and this is her weird way of communicating it. 2. She has a “secret” boyfriend, or likes some guy and might hookup with him soon. 3. This is some sort of weird head game of hers. Is this some thing in girl language that I’m not understanding? Is this a common thing? Am I on the right track or just stupid?

[quaranta]

That is not found in any "girl language" dictionary I'm afraid, I would be confused as much as you are.
Assuming to "believe her" for a second, the way she pictures things is anyway weird, she doesn't even know if the future boyfriend will be jealous of her friends (this is not granted, nowadays anyone has opposite gender friends among the young generations, my boyfriends never had a problem), and doesn't even consider how toxic a partner like that would be. Is this the ideal partner she wants? Possessive, controlling, unable to trust her? I don't think so. For sure a close friend can't be the "main person" anymore if a partner enters the scene, but that doesn't mean you stop "talking" at all, why?
So, in my opinion, this is an awkward game that means something else.

I'll throw some interpretations:
1. Agree with your conclusion about possible feelings, simply because people being weird and committed in something they do mask some "motivation" behind, big enough to keep the thing on instead of dropping it. And as you say, she might not trust herself around you, if she has a boyfriend (although if she would be able to take action there, why not now?).
But also, she might be doing that just in order to cause a reaction from you, she tries to make you picture that you could lose her, in order to check how much you "care" about her, testing the waters about possible reciprocation. You keep not reacting in the way she "wants", so she keeps trying extracting that reaction. Considering she calls herself an incel, maybe the why she got no experiences so far is because she is awkward as hell in these things and all she can pull out is these strange pathetic games.
I think you can uncover this by talking about a girl you like and how she is responding to your inputs, maybe taking longer to respond to her text for a couple of days, to test -her- reaction this time.
2. Agree with you conclusion about possible incoming boyfriend, someone she crushes on or is hooking up with, etc. Maybe she wants to avoid conflicts and is bad at dealing with them, so tries to make very sure you have no feelings for her and that she is free to go with this guy without causing huge mess. Although, if she didn't want to cause conflicts and to "prepare" you, she would probably not tell you something so drastic and not realistic like "stop talking to you". That is rude enough to imagine a possible conflict, alone, because it's not just like saying you must be prepared to be the second one, but also that she doesn't care at all about this friendship with you, to the point she can drop it completely for the sake of some remotely imaginary jealousy of a boyfriend who could ban her from even talking, with male friends.
Anyway, if this is the case, you would notice her getting more distant recently, not initiating conversations, not sending the same amount of memes out of nowhere, etc. Her communication and attention needs would be shifted on someone else to some extent, even small.
3. Maybe she is doing that for herself. Maybe he has no feelings, but she feels anyway uncomfortable in feeling affectionate to someone, or to have a closer bond than normal, in general. So she tells that in order to make it clear to herself too:"I can drop it whenever I want, I'm not so attached", sort of things. Considering she calls herself an incel and is around your age, if she is alone probably it's because she has some social phobia about getting closer to others, or things of this sort that "cause" her status, and that might cause her constant trying to keep distances with you. To not feel vulnerable, accessible, or just in an unknown territory.
Check if she dismantles other bonds around her in the same way, diminishes people who are vulnerable to each other, or is proud to be independent and cold.
If she is like this, exposing her with direct questions would give no results, she would back off.
(This point, though, can be also added to point 1, if point 1 is true).

[Pegases]

She wants you to be her boyfriend, so she's trying to coerce you into thinking about what it would be like to lose the friendship. Women have very odd ways of showing men they like them, and this is one of them. Perhaps she feels awkward bringing it up any other way, so this is the best she could come up with. Long story short, even if she did get a boyfriend, she'd still probably say yes to you if you asked her to be your girlfriend.

[Berethor]

Seems like she want something more from you, also her boyfriend might be a jealous type.

[Iron_Man]

Bad conversation ask her why?

[Anonymous]

Beats me. This makes no sense at all.

[Asker]

Is that sarcastic?

[In_Trance]

Wasting your time