I understand if he's feeling nervous, but they're close enough to lend each other manga volumes, so it's weird that he's unable to exchange contacts with her due purely to his nervousness (imo at least).
I think the thing people are missing here is that MC seems to have some form of anxiety in general, and has difficulty talking to basically anyone. Add nervousness because she's his crush, and it makes sense he'd lose heart.
Remember guys, gyaru-oh with 20cm penis and rich ugly bastard who appear in NTR hentai exist because of beta wimpy ass MC like this. Don't be like that.
Apparently none of you cassanovas were ever a shy, awkward teen who struggled with and agonized over getting up the courage to talk to girls. I remember those days all too well.