This ↑ is core of your love affair. I'm sorry that after all you've been through, she's yo-yoing you emotionally. Women are affectionate and indifferent, because we expect them to be that way with no consequences (behavior modification). If you are mystified as to why she acts that way, it means that she is not checking in with you about what is affecting her life (studies, family, job, etc). Your time together should be an island of sanity away from daily stress, where you recharge.

When women are cold and distant chronically or disappear for a couple of days, it's a part of women's typical exit strategy for ending a relationship:
1.) Less interest in seeing you, planning holiday's together, not talking sweet talk to you, etc, 2.) calling less, and 3.) some concocted fight/conflict to either force you to break it off with her or blame you for something petty. Rethink why you value her, what is valuable in the relationship, and what kind of relationship/female behavior would make you happy. Your investment in her clouds the above dynamic. Then talk to her and make a choice. Texting is not useful- talk is useful. If you decide to break it off, do not give lengthy explanations- just an acknowledgment that neither of you wants to be here anymore, you should re-create your lives, thank you for sharing your life, and best wishes.

Good luck.