I wouldn't just get him without both people wanting him. The ask for forgiveness later theory doesn't really do well for marriages IMO. If I pulled a stunt like that we certainly wouldn't be keeping the pup. Same would go if Matt did something like that with something that we hadn't agreed on. I just don't think that is the way to go about getting him. Maybe ask if the two of you can just go LOOK at him... maybe he will give in when he sees how cute he is. He may just fall in love
If you get him with him saying no, he may end up resenting the pup, which is something you certainly don't want.