Confusion & adoration

I had been using a dating app for a while and over a month ago a guy started to talk to me (for privacy sake, let's call him Jack). After Jack and I became more comfortable with one another, we shared connections on Facebook and Skype. We were constantly in contact, whether we were out or at home, text or video. After about two weeks, he asked if he could come see me, but seeing as I'm a college student and had exams at the time, I agreed but set the date for just after my exams (which would've been three weeks later) so that we could spend actual time together and he wouldn't waste gas (he lives 2 hours away). A little less than a week later he decided that he wanted to see me, even if just for a coffee date. So, he came and we spent the night talking away and walking down the pier in my city.. Throughout the evening we discussed our past relationships more in-depth (as we had been on the topic a few times on Skype) and he seemed to still be affected by his last relationship, which was fairly recent. However, he assured me that while he cared for his last girlfriend as a person, he had eyes on someone else. After that, he visited about two more times, each time he seemed even more captivated by me. As a student studying human behaviour, I believe that he was certainly interested in knowing me, rather than wanting anything sexual. So, we set plans that after exams I would be spending a week with him at his home. Once that week came, he wasn't feeling well and had visited the doctor's the week before, yet he still came and took me to his home. When I got there, however, he showed almost no adoration for me. I wouldn't catch him looking at me as he had before, he hardly smiled and it seemed that the situation made him feel awkward at times. I felt that it was just due to his illness, so I didn't comment on it, but I did my best to keep him company. When we slept there was nothing more than cuddling... He didn't kiss me the entire time I stayed. The majority of the time I was with Jack his ex would message him, with comments about her new boyfriend, how happy she was, etc. Jack would tell me about this, then he would play these games with her as well, sending a "random picture of a girl" to her, making her believe that he found someone too... I let him know that taking part in her games would not let him move on. I met his father the first two days I was there and the third day Jack actually took me home, although he said multiple times that he didn't want to. The entire trip home thoughts went through my head; "Is he taking me back home because his ex wants him back?", "Did I offend him?", "I really hope this won't be the last time I see him..." I eventually worked up the ability to ask if he would be coming back after he dropped me off, to which he said 'of course', then continued to talk about his ex for a good portion of the ride. A day passed without us talking, I wanted to wait and see if he still had interest. After a day of silence, he messaged me; Jack: Hullo O_o Me: Hi, haven't heard from you in a while. Jack: Yeah, I've been bleh. Me: Oh. I was starting to feel like you didn't want to see me anymore or something like that (probably just due to my anxiety). How did your doctor's appointment go? Jack: Well, I did come to the conclusion I'm not ready for anything...so I do want to be friends. Me: Well, that's fine with me. I'm confused.. How can someone who held such adoration for me just end it in an instant? This may just be a product of his ex messaging him while he's ill, but I've started to really care for Jack.. I suppose the only thing I *can* do is to wait and see, but I'd still like to hear other people's opinions. Thanks in advance.

Skye, regardless of what Jack says, he's not over his previous relationship. It's up to you whether you keep him as friend because that's all he's ever going to be until he gets past his ex.