2 male guineas. 1 attacking the other after a peaceful 2 years, WHY???

[Tootsie]

I have 2 male guineas (those are my only ones) and they have been here almost 2 years always got along until about 1 month ago. Then they started going to separate coops at night and now the one agressively chases the other to the point where it hides in fright. I am baffled at why after all this time there is trouble?

Any suggestions?

 

[Aj1911]

mating season maybe? or could be he sees him as he's from a different flock since they are going into separate coops.

get a few females it might help a bit.