You have to get the confidence to escalate sexualy further. With no sexual tension = no relationship. So next time you see her, look very sexual to her, with the frame "I know what you want and I'm about to give it to you." Then start kino her, escalate, escalate, kiss her, escalate, escalate, have sex. Don't wait too long with this.
You might see this as a risk but this is the only way for not falling in the friend zone. You should give a fuck that she is less affectionate than before. If you don't want her as a friend, what do you have to lose if she rejects you if you try to kiss her? (and eventualy, if this might happen (small chance), you can just walk away then and leave her behind and she will try to get you back).
Have fun
