For me this is another one of those, 'erm, did we all read the same book?' Because this grump was not lovable, nor was he particularly interesting, or kind.
THEN, you have a lot of plot backpedaling, and then things getting resolved without it being stated for clarity, or even...to make it smooth. It's just very haphazard.
"Well--you just didn't get it there's a lot of twists." Yeah, but the way they're all introduced is what the problem is. It's sloppy writing. And that's really unfortunate for a series opener, that's all I'm sayin'.
Plus, I just want to emphasis that the heroine in this is super, super whiny. She's a wallflower, but in a doormat way, not a minding her business way, and that's always UGH to read. Also, I have never met someone (who successfully completed advanced schooling for a title) refer to themselves as LESS THAN that title in their work. Like, yes, she's a vet. tech in pay, but her credential's don't change just because of the jobs she does under contract. She's still a licensed veterinarian. And if she completes the tasks of one when her boss is out...she's obviously qualified? Idk, that detail is so obviously warped for the drama factor but damn.
Good luck!