Fox, I'm with Blanca 100% I think you should move on. I went through a similar scenario with an ex whilst at uni, every now and then she'd come back to me despite her seeing other guys. I was ridiculously AFC back then so I'd always take her back, it took me a while to realise she was just after something from me or quite simply after attention.

The thing to do is cut communication with her, don't text her, call her or arrange to see her etc. If she calls or texts you then fine, be polite and civil with her but don't put all your time and energy into this one girl. I know its a cliche (and I hate the term) but 'There's plenty more fish in the sea', the point is to have a mentality that women are abundant, once you have this locked down its a real blessing.

No longer do I pine for one particular girl or suffer from oneitis. I used to suffer from crippling oneitis, once you realise that women are everywhere and you are worthy of them then you will soon forget this one girl.

'Shes off to uni end of next and worst thing that could happen is I could end up being just her mate.'

How is that the worst thing that can happen??...if anything I think thats the best thing that could happen out of this.

Let her go, and let yourself go from her. It maybe difficult for the first few weeks but soon enough you'll feel free and rejuvinated. Go out have interactions with and meet at least 10 new women and then ask yourself 'Was that girl really all that after all??'.....my guess is the current feelings and perceptions you have of this girl will change.

All the best.