She's was/is super into you. She's been open about it. In order to protect yourself you have chosen to be aloof with her. As her caring for you has grown deeper, she has looked to see that you feel the same. She only sees your aloofness. She believes there is more to what you feel for her, or at least was hoping there was. She couldn't find it. She wanted to know you would miss her while she was gone. You were aloof. You two spoke briefly while she was gone but never really connected. She really wanted to know (was hoping) you had missed her and were anxious to see her when she returned, just as she had missed you and was anxious to see you. You were aloof. That response deflated her and all her enthusiasm to see you. Her feelings and caring for you, felt unreciprocated to her. She likes/liked you a lot! She also wants/needs to be with a man who desires her and is affectionate with her. Aloofness does not convey that.
Women need to matter to the man they choose to be with. She returns from a trip away and you come across as indifferent to her return. She reaches out, the best she can, looking for reassurance that you care about her. When she doesn't get it, she's left believing you don't really care for her as she had hoped. To her this signals, that she's invested herself in a guy who "just isn't that into her." Even though it hurts, she considers she'd better step back, take some time, and reevaluate. She was still desperately hoping that you cared beyond the impression of being aloof. She wanted to know and be reassured that you were into her, more than your aloof presentation gave off. Your response? You too could use some time and you wish her luck. That wasn't just aloof, that was in your face dismissive. You conveyed you don't give a sh!t about her at all. She's a bother and if you never talk to her again that would be fine. That's what your words conveyed to her whether you intended to or not.
Now you are here at SS wondering what happened. She's in her world wondering the same thing. She was soooo into this man. The only conclusion that will make sense to her is, "he just wasn't that into her." Her friends will say the same thing. They have nothing else to suggest otherwise. Meanwhile, underneath it all, you two could have been a really good match. Great potential lost to miscommunication and misunderstanding. So disappointing, even to read about. I sooo wish men and women could better understand what the other sex really wants/needs, is trying to say.
TL;DR bold above