Golbat evolves into Crobat if its friendship is between 220 and 255 (inclusive). So the friendship checker will say one of these 2 things if Golbat's friendship is in that range.
"It looks really happy! It must love you a lot."
"I get the feeling that it really trusts you."
(note that the second quote can be said if Golbat's friendship is less than 220)