Hmmm? He is in love much earlier, but in denial. When he really says it to Grayson, that is a different situation.
Dane loves Grayson, so it's not one sided. But he is for a long time in denial as I mentioned.
No, he doesn't, but likes animals more than humans, and if it's his way to describe it, so be it. The problem is probably the ear twitching ( that's something you see animals do), but he inherited that from Koi, and Ashley is weak for it too.
And it needed to be slowburn, you don't have only one character with serious problems, but two.
What you write completly leaves out what kind of problem Dane has, so it gives a wrong impression of the situation. But that would be even more spoilers.

i remember its only when grayson was abt to die or smth where red hair admit he likes the guy lol and that's chapter 160+ their development was sooo slow even a turtle is faster than them. also, what i don't like abt this pairing is it seems to me as tho red hair only sees grayson as a dog ╮( ̄▽ ̄)╭ even novel reviews of it can tell how it feels one sided until the end. like red hair only settled bc grayson is an obedient dog to his eyes and he loves dogs so ( ̄∇ ̄") don't expect any romance in here, there's not really a reciprocity on the red hair's side (take this with a grain of salt)