Your boy has to wait 4-6 weeks after the operation until he can get together with his lady love in order to prevent any accidents.
What you can do is having them next to each other side by side so they can see and smell each other and become friends through the bars.
Introduce them somewhere with lots of space. Your boy will probably go into testosterone overdrive and temporarily lose his brains. The girl will be less than impressed, unless she's in season, but they have to work it out. After that, they should be very happy together.
I have had my neutered boy with one lady at first; he's up to four now and a very happy boy indeed!
I will ask the mods to move this post to a better section.
