You're friend zoned and the booze make her flirty with you. That's pretty much it. You said several times that she acts all interested when you guys drink together. Word to the wise, women get very sexual when they drink. That's just how they work.
You are friend zoned, though. Women have two things they need in terms of relationships: Emotional needs and sexual needs. You provide the emotional desires she wants while she attempts to acquire this other man she's interested in. That's why people get friend zoned in the first place. The woman will realize you give them all the affection/attention they want without the risk of you being a scumbag. Meanwhile, they chase after a scumbag because they want the sex with said scumbag. When the scumbag treats them like shit, it doesn't matter because her emotional support is there.
When finding a person to fulfill both needs at once becomes difficult, they resort to using two people for separate needs.