it seems like you are sort of needy man,
you are extremely focused on a specific girl, you are putting too much thought and energy into this, just don't try so hard
think of it like this, when you like a girl, if you were to not text with her for 2 weeks, then text her again would that make you like her any less or would it not effect how much you like her at all? now consider this, you just meet a girl who physically you rate 5/10, lets say you are semi interested in her sexually, but basically you are on the fence because you think you can do much better and it is not a girl you personally would have chosen to approach, but you're single and this girl does all the work for you, she approached you, she gets your number, she calls you first, now, what do you think you would prefer, her to start calling you every day and trying to have conversations that are as long as possible about random girl shit, or her to call you once a week, and she just invites you out cause she wants to suck your dick?, now reverse the rolls, girls are no different in this respect, you don't have to ''maintain interest'' if it is there, it is there
now, imagine this, girls like that emotional high of a guy who has good game, it becomes like a drug, but imagine if you give that drug out too freely all the time, it sort of loses it's potency doesn't it?, think of it like this, lets say you call a buddy who you just met, this guy is really funny, like pro comedian funny, so you want to text with him all the time so that you can laugh and feel good, but as you keep texting with him more and more, you get used to his style of humor and become desensitized, the more you text the more chance he has to say some things that are not so funny, and since you are so accustomed to that high level of emotional stimulation, as soon as he can't deliver at that same level, your opinion will sort of just drop off of him and you get turned off to his humour since it isn't as stimulating as it once was to you, and all of a sudden the idea of socializing with him becomes less of a rare privilege, and more of a comfortable expectation, you just become de-sensitized and expect that you can get that attention when ever you want, and the attention it's self becomes less valueable
now OTOH, imagine this same buddy who was comedian funny, would hang out with you, or hit you up once a week, give you smaller doses of his comedy instead of giving you hours of material daily, all of a sudden his attention is more valueable, it's more of a rare thing for you, you are actually excited to get a call from your hallarious buddy that has some funny stories to tell you about his week, rather then ohhh... steve is calling me again, this is the 2nd time today, I don't want to here his story about how the elephant pissed on him again we already talked today
now normally guys don't use their phones to just have random conversations with other guys, and they end up friends and have good rapport anyways, you know why?, because guys generally aren't needy towards other guys, you call and text a girl more often because you want her approval, you want to get her to like you because you care, with a guy you are more likely to be indifferent, you just assume the guy does like you, calling or texting him constantly just to ''talk'' or to ''maintain interest'' from him, would be fucking weird (unless you are a really social phone person), you just call your buddy when you want to hang out, because you know he will meet up with you cause he likes to chill with you and values your company
now what is the point to this big long essay of bullshit?, stop being incongruent and seeking approval out of neediness, if you wouldn't text/call your guy buddies every day to ''maintain interest'' why do you do this with girls?, game them in person so they are thinking about that awesome guy they met and leave them wanting more of that drug that they crave, that premium grade-A attention, and give it away sparringly
stop over analyzing all your situations, stay outside your head, be indifferent to if a girl fucks you or not, just fuck around with her and have fun, if she really enjoys your time, she will start calling you looking for that attention, and you won't have to do shit besides tell her, that you are doing something and don't feel like talking, but you guys should hang out on Xday (and if she isn't calling you, then call her to ask her out, instead of calling her to build interest, if you couldn't generate it in person, it's highly unlikely you can do it over the phone)
and if you are actually indifferent and treat her like you would anyone else, male or female (obviously you hit on her/flirt though, compared to a male buddy), you know what will happen?, she will show up on Xday, and you know why?, cause she actually wants to see you, cause she wants that awesome attention from you that she isn't getting 24/7 (assuming your attention is awesome and you're an interesting guy to hang out with cause you have tight game)
if you're too needy, girls will flake you, if you don't get to know them well enough, girls will flake you, if you are projecting way way way below their ideal image of what ''type'' of guy they want but they like your game alot, a girl will contact you all the time for attention, but she will flake you, if a girl is sexually unavailable to you, but likes you, she will contact you for attention, but she will flake you
learn how to screen girls before hand for compliance and sexual availability, if they are a waste of time, then don't waste your time, meet more girls that don't offer up these types of problems, instead of trying to fix problems that are not your problems, and other then that, don't be needy and actually build a rapport before you ask a girl out (do this in person while flirting etc., avoid doing it over the phone if it can be helped, if it can't, what ever it's fine to text/call, just don't overdo it and ''over game'' her)
as far as this chick friend zoning you, all I'd reply back to that is, sounds good cutie pies
then she would get put on ice, and I would forget about her, stop contacting her all together (NC) and meet other girls, then after a month or so of NC, you can hit her up, and try all over again, and next time try not be as needy and cut yourself off from her as soon as you start caring about her and how it goes with her, simply keep it casual, who cares about some girl, hit on her get in her pants, sex isn't a big deal, if she thinks it is, she is a weirdo and probably has sexual hangups, if thats the case cut her off from your attention and find a girl that doesn't have these issues, the solution to all your problems, is find a different girl who doesn't have these problems, then before you know it you will just have a whole lot of girls calling you, instead of the other way around, and they will be woundering why you don't like dealing with their problems or facilitating their need for attention when they won't go out with you
also, don't take anything a girl says seriously, she says ''lets be friends'', this means jack shit, you escalate and test compliance when you have the logistics, you don't fall into her frame, you set your own, if she is actually not sexually interested, she will be non-compliant, watch what she does, not what she says (although you should be aware of what she says, don't take her opinion or perspective on things too seriously)
GOOD LUCK