NaomiVonkreeps

Hi everyone. I'm new to the forum and new to owning normal zebra finches (although not new to owning birds). I accidentally became a finch owner when one appeared in my backyard, eating the seed I feed the wild birds. Since I live in Canada, I knew I had to catch it or else it would have died once the temperature got cooler. I caught the male finch, had it in a small cage for 2 days before going out and buying him a friend (another male) and a bigger cage. The two got on famously and immediately started preening each other. I've read that you should not give them nests if you have 2 males, however I did provide them with 2 nests and the two would sleep together in one (so cute). I then decided to upgrade their cage to something even bigger so they would have a lot of flying room (31-Inch long, 20-1/2-inch wide, 40-inch high), I added a third nest just in case so they would not have to fight over one. They lived happily in this cage for about 3 weeks. Preening and sleeping together until one day, the bird I caught in the backyard became aggressive and now chases the other one around. There is a bit of pecking but no feather pulling, and no one is getting injured. One is simply chasing the other one around. I noticed he makes a particular sound and opens his mouth before chasing the other. And sometimes the other one will chase the one that is usually the aggressor. I've removed all the nests for a week, rearranged the entire cage (in case they had become territorial). They still fought. I put the nests back in. They fought, and slept in separate nests. I once again removed the nests. Annnd because I felt sorry for them I eventually put the nests back in. Now they still chase each other around but are back to sleeping in the same nest. I am not sure what to do at this point. I've considered several times separating them. The chasing/fighting isn't constant. They will sit beside each other and preen themselves. I've also added clothespins to some of their perches to give them their own space. I just don't want them to be stressed out. Some people have advised me to add more male finches, but I don't want to add more if the aggressive finch is going to chase after all of them. I do not want females as I'm trying to avoid any breeding. Sorry for this LOOONG POST. Any advise would be very much appreciated!