Female Suddenly Rejecting Male?

Hello everyone!

So I have a female het pied I've been trying to pair with a male pied. I put them together for the first time on 10-31 and within an hour, they were locked, and remained locked for a good 15 hours. Since then, I have put them together twice more, without any luck. He has also been put with another het pied female and have locked every time, no problem.

Before their first pairing, this female was taken to the vet for super runny feces. She received treatment and has been totally fine since. I waited about two weeks after her last dose of medication and a normal fecal before pairing them.

My male seems interested, but just isn't apparently able to do the deed with her.

Any theories as to why she might be rejecting him now? I can't imagine it would have anything to do with her vet visit when that was prior to them even locking the first time. Just looking for clues as to why she might be rejecting!

Thanks!

Since they did lock a few months ago, she may have ovulated. Has she shed recently?

She shed approximately two weeks ago. I only started cycling them in early to mid October so I wouldn't have expected them to stop locking so soon but
who knows!