Thats one of the dangers in fostering, getting too attached to let them go. We got very attached to our last foster, DJ. (see my webshot albums)

After seeing him survive parvo and his broken leg healed, we got emotionally attached. We try to spend our energy on our pets. A few are getting up in years, and we want the remaining years to be great.

Keeping one foster may mean there is less space to save another.