can i keep him?

Rasputin goes to the Animal Rescue League Wednesday night for adoption. You can see that he is extremely attached to me. He came in as a hissing, growling stray, likely with little contact with people. He's such a sweetheart now. I want to keep him so much my heart aches when I think about having to take him in. But...if he's gone from a semi-feral into this sweet lovey-dovey guy, then I guess my job as a foster mom is done...and he needs to go to his permanent home. But it won't be easy to give him up.