13? That's nothing, a certain nightmare I know all too well irl seriously dated a new guy each week roughly..
Went on for atleast 20y while I knew her, but likely longer outside of me knowing.
(She never really learned, and usually moved to a new city when she got too infamous.)
Her relationships only started lasting longer after she started pestering me for advice,
which was quite a struggle to give since she's pretty bad at listening too.
Back to the manga..
This guy's not that bad but rather just insensitive,
not helped by the fact noone seems to have bothered telling him or giving him an honest answer.