Coridon is pretty much your textbook Pastoral shepherd. Even his name is textbook, appearing the first pastoral poems by the poets Theocritus and Virgil. Coridon tends his flocks, plays his pipe, and most importantly, longs for the love of Pastorella that he'll never actually acquire.
Rule numero uno for pastoral shepherds is that they are always in love but will never have they love returned. It's a hard life. In competition with Calidore throughout the end of Book 6 for Pastorella's attention, Coridon doesn't stand a chance against Calidore's bravery once the brigands attack and capture the shepherds. Coridon acts as an important contrast to Calidore; his cowardice suggests that while the life of the shepherd may seem idyllic, it can come at a cost.
Calidore's hardened nerves of steel are not only attractive in Pastorella's eyes but also ultimately necessary in a time of crisis. But don't feel too bad for Coridon. Even though he doesn't get the girl, he does get a big, lovely flock of sheep to tend at the end of the poem. Consolation prize!