Hate to be this way but either you have been lucky (most likely) or your female has been gravid a lot ( very bad for her will shorten her life). To tell a new veiled owner, who would not know how to tell if they had stressed chameleons until one of the two died, that putting them together is very irresponsible imo. I don't feel that veileds should EVER be kept together, but that is just me. If a knowledgeable keeper elects to do it so be it. They know what they are doing and what to watch for. However please don't offer this type of advice to a new keeper so their first experience with chameleons is most probably seeing one die.
I setup this account to chime into this ancient thread because it came up highly ranked in google. I kept chameleons as a kid with a blend of success and failure.
Found this thread when considering re-entering the space with my own children. I have to share that the greatest success I had was a 300 gallon vivarium with 3 Veiled chameleons, 1 male, 2 female, living with a blend of other predators (tree frogs, salamanders, and geckos mainly, one uncharacteristically large leopard frog, and one green tree snake). We (my best friend and I) were not particularly smart about it, we built the enclosure when I was in 6th grade. The arrangement had a bunch of random house plants, acceptable ventilation with good daily misting and one of those early fog machines from the 90's. Probably the saving grace was the very eager application of a variety of live prey animals to the habitat always powdered in some form of vitamin dust. The Chameleons all lived over 5 years. The ground gecko lived for like 15 years, ending up in the hands of a distant relative, the salamanders out lived the arrangement and similarly went off to reside with distant relatives when time to depart for college. The tree frogs were cartoonishly chubby and yet acrobatic. The failures of this arrangement were the green tree snake didn't make it a year, and we started with some smaller climbing geckos that got eaten by the chameleons. We even subsidized anoles when they were bulk discount at the local trade swap, if they got eaten, so be it, but a dozen in there could even reproduce and last for about 18 months and take lots of stress out of the social hierarchy.
I don't think our chameleons ever mated, the eggs were always infertile, or didn't hatch at the least.
I did see some of those dominance displays, not really fighting just lots of "don't come over here" type behavior. Until they'd sometimes just hangout... then be surprised to be so close and then spread out and do their dances from afar.
I'm NOT advising keeping them together. Not in the slightest. It was the 90's, I didn't even know what the internet was and came into the hobby without even knowing how to properly pronounce the word Chameleon.
Just sharing an experience. My take away is probably this for most any successful endeavor into animals husbandry... exceed the minimum habitat requirements, it grants you a great deal of grace in the care of the animal, weather swimming, flying, climbing or crawling.
Particularly for terrariums, particularly for arboreal animals where most of the habitat is air, it is just so darn easy to build a oversized cage for the money. And if you are gonna "experiment" having done more of that in aquariums as an adult, have a backup plan. Have a spare home waiting just in case things go a little sideways.
And since this is a predator pet I think its ethically based to suggest in any LARGER "social" environment to consider a "dither" animal. An expendable mid tier animal, a notch above food, not intended as food but as something to act as a buffer between the predators need to eat and the predators social angst. In fish tanks, guppies, danios, rainbows and others serve this function well for many community tanks.
Having typed out this whole reply, I'd surmise our idiotic success here probably came from 4 things, over large environment, dense dense planting to brake up line of sight, constant availability of good and varied food sources, and the sacrifice of our green anoles. I mean with perspective I'm amazed the chameleons didn't eat every other animal in the tank then kill each other... But this also outlines the original response from summoner12, that
the RULE is don't keep them together. If you want to try with any hope for success, realize its a completely next level endeavor.
The OP clearly has moved on in life but wanted to leave this here to inform the discussion for what its worth.
Cheers!