We were in Secret World of the Okapi, viewing one of them indoors, when they let the other in.
A keeper was also in the public viewing area. There were only maybe 5-7 people around and he said we may (or may not) want to stay watch as they thought she might be in season today.
We stayed 5-10 minutes before we had to press on and this was as close as it got, so I can't report whether anything happened or not I'm afraid!
There aren't great photos, but I didn't want to use the flash.
In the next photo she looks very relaxed standing right next to him so finally it looks like a compatable setup with thse two. His arrival (once she decided she liked him) might well have suddenly stimulated her oestrus cycle-whereas a male she wasn't happy with can repress or upset the cycle I think.
Ysterday they were trying to mate. The male kept trying to mount the female but she kept moving away. A keeper was watching in the public area and also another was from the side of the enclosure.