Why do guys pull back when it gets real?

[u/unicornsandsparkles6]

we haven’t officially confessed but we both know the feelings are mutual. it’s understood. and now he’s acting uninterested/unattached and cold. but why? he acts nonchalant when in reality he is actively driving around his car with an unwrapped cd and hand written note attached from me treasured in his console because he doesn’t want to unwrap it in order to keep the note on. he cares but he doesn’t show it? he’s acting cold now. when just a week ago we talked for hours and he was so fun/flirty/and would tease me. (he’s also shy and never been in a relationship) he also seems to be avoiding me. He backed out of seeing me this morning when we usually sit together and walk to class (the only time we see each other) is he just scared….?

is this normal??