Don't take not flaring for granted. My male, Blue Jeans, hasn't been flaring at his neighbor for a while and all of the sudden he's started bubblenesting and flaring again and darn it if he didn't rip up his neighbor's fins through the divider. I'm almost 100% positive that is what happened because the poor boy's fins (including his dorsal) are torn to shreds.
I'm doubling up the divider tonight. Blue Jeans has lived in divided tanks pretty much since I got him a year ago with no problems. Now all the sudden he's the bad man on campus.
*Be smart.. Do your research!!*