Cant work out wot's in her head!!?

As u can see from my last questions, my ex split from me last april. well as luck would have it she got back in touch again in july, been treated bad, wished she had stayed with me! we got back together, ii was so happy. we booked two holidays, one after her sisters wedding. bought �1500 engagement ring she really wanted it, i love her so i bought it, show how much she means to me.planned wedding next year in jamaica. went over for sisters wedding, (NI) she finished it the next day. I book flight home, leave in the ealy morning by taxi to belfast, hurt to much to stay, she wondered y i didnt say goodbye! text, saying i'll b in touch, sure enough 2 weeks later she texts, just chit chat. wot is going through her head, she couldn't belive i wanted her back after the last time, now she has done it again. please give me advise so i can sort my head out. thanks