Someone left their dog with me 90 days ago and now wants to get her back

Location: Florida

I had an old friend, who is unknown screwup of to stay on and off at my house for the last several years. A year and a half ago his ex called and told him that she was taking her dog to the pound because she got a new puppy and didn’t want the old one anymore. Because he was staying with me at the time, the dog also came to live there. He was in and out of my home a few times over that year and a half and I let him stay with me again five months ago

Around June 15, he met a girl online who lived across the state and she came down to visit him. They stayed in a hotel and he left the dog with me. At the end of that weekend, he decided to go back to Jacksonville with her, leaving the dog in my possession, but I would not have known other than the fact I ran into him on their way out of town. Since then, he has only asked about the dog two times. Each time suggesting he might come get her. I have been paying for her food and vet bills as she had an active infection and had not seen a veterinarian in years.

Today he messaged me to inform me he will be coming to get his dog as he now has stability. He’s had the job for four days and last week he asked if he could live with me again because he was going to leave the girlfriend because she was a drunk.

My question is, does he have any legal claim to the dog? He has not paid for any of her care, including food. While she was in his possession, he never took her to the vet, so there is no paper trail of ownership. I love my friend, but he has no stability in his life and now only wants the dog because the girlfriend lost her job and wants the dog to keep her company. The girlfriend has never met the dog.

I’m really worried about giving this dog back and that she will just end up in a horrible situation. We grown very attached to her and so has my elderly dog. Please give it to me straight.