Hi,
This isn’t unusual, and probably not permanent. Both are at a peak breeding age, and most likely one has become more hormonal than the other. You might try splitting them up, but leave the cages side by side. If you handle these birds, then it can be causing some confusion and jealousy. Since their instinct is to bond with just one bird, they can feel torn between you and the other bird, and jealous of the other bird when you handle one. Wait and see if they settle back down after being separated and giving them time for hormones to settle back down.
Thank you for asking Lafeber,
Brenda