Because he said yes, and then seems to have changed his mind. Mainly I think because of the potential for putting a cat flap in 
I've just been contacted about a gorgeous girl cat who needs to be an indoor cat for at least a few months as she recovers from being poorly. She's beautiful and I desperately want to give her a home!
However I need to do that final convince on OH. Should I just go ahead because he did say yes a few weeks back?
I do have to say OH will happily look after any cat once it's in our house, he's had cats growing up and I know he'll fall in love very quickly, I think it's just that he is an eternal procrastinator and is useless at actually making a decision...