The personalities of gourami can be very testy, especially the 3 spot varieties that you have. I've only personally kept dwarfs (so far...I plan to change that soon!), so let me tell you a little story about a funny situation that happened with mine to show you just how their mood swings are...
I have a 55 and 29 gallon. My first fish was my male powder blue
DG that I kept in a 10 gal in my dorm room, but I decided to let him "rule" the 55 when I got it. I figured the tank was big enough and that there were plenty of hiding spots, so I tried adding a male flame DG about a month after putting my powder blue in. Edward (powder blue) didn't like that a bit and was chasing and nipping the other guy constantly, which worked out fine because I just moved the flame to the 29 gal because I hadn't done much with it stocking wise. Time passed, got another calm male DG for the 29, and those two were getting along famously...and then my 29 decides to re-cycle after I had added meds that killed the cycle (didn't realize that before hand...I'll never do that again). So, reluctantly, I moved everyone upstairs to the 55 temporarily, which technically way overstocked it, but hardly any of my fish are full grown so there was plenty of room long enough for the small tank to cycle, other than the fact that I was adding 2 male DG's in with my very spoiled and territorial Edward. Surprisingly enough, Edward is being a little angel and only gets angry when either of the others try to "hide" in the floating plants, which Edward has claimed as his territory. As of now I'm actually planning on keeping all 4 of my DG's in the 55 (3 males, 1 female) assuming they'll continue to get along, but I'll always have my 29 as a backup in case an aggression issue arises again.
So, obviously not the same breed of gourami, but things can change. Have you tried giving the male a "time out" while re-arranging the decor to see if that calms him down some? It may be something to try.