I caught a level 35 Kirlia in the Underground in Brilliant Diamond recently. The footprint guy checked her footprints and told me that she felt neglected as I was paying more attention to other Pokemon more. This has been going on for weeks too. I even gave her a soothebell but nothing seems to be working.
Dr. Footstep has five different ratings for Pokémon friendship. These reflect the Pokémon's responses as shown on the Friendship Checker Pokétch application. The lowest level of friendship will usually only be seen on Pokémon that have been treated badly, or on certain newly-caught species (such as Legendary Pokémon, Ralts, Buneary, and various Dark types) that naturally start with very low friendship.
Source
Level 1: "Aww... (player) only plays with other Pokémon... (nickname) feels neglected... Maybe (player) doesn't like (nickname) very much? (nickname) will try harder for (player). Please be nicer to me!"
The above quote you get when a Pokemon has 0-69 friendship. Man, your Kirlia hates you! That's okay though; Kirlia has a base friendship of 35, meaning you probably haven't done anything to make it hate you.