What's going on? How do I make him like me again?

[Sophie]

I used to fancy a friend of a friend, let's just call him bob, last year. I got over him a while ago but now he's started fancying me. I would often catch him looking me and all his friends would often say to me that he wants to kiss me lmao. :L We have 2 lessons a week together, and on Wednesday he asked me out on the school emails. I said I'll think about it. Everyday all Bob's friends would ask me if I said yes or no. I said I didn't know. I didn't want to make a fool out of myself and say yes just incase it was a joke. I could tell that he was serious because he was shy and blushed alot but I was still kinda nervous. I did like him a bit but I wasn't sure so I just wanted to give it time. After a while they stopped asking me if I said yes or no. I messaged him on Facebook saying "is it true" and he didn't "read" it but the next day when I was walking home I was behind him and he was with a friend and we were talking and when we had to go different ways he said "it's not true by the way".

Did I do something wrong for him to lose interest? WHY did he lose interest? Or is he just saying it wasn't true because he thinks I rejected him? Tomorrow it's the last time I have a lesson with him because our timetables are all changing. What should I do? Thank you in advance, sorry it's kinda long lmao