YES! The male will eventually aggravate the crap out of the female when he comes into sexual maturity. My Drako was housed with his sister Aries since they were little babies but as soon as they both hit a year old WHAM! he would try to mount her, bite her nape ( back of her neck), he would flare his body out and circle her and everything he could do to make her submissive and be the under dog. As for the book telling you hty eget lonely..well they get lonely when they r in the mood! Lol
but actually bearded dragons really like to be on their own knowing that they see any other dragon around them they take that other dragon as an intruder not a buddy to talk to. I would recommmend you to get a 55 galoon for both of them but it really depends on their size, I just recently bought a female from a member on here and she is way more buff than anythign but she is wide and fat in toehr words so I wen twith a 75 gallon instead. Just be carefull if you let them close to each other, when your not looking is pretty much when he might do something to her...or the oppisite, I had a german giant female that was just up to her last nerve with one of my males that kept bothering her and one day I made the mistake of putting them in the same crate to take to the vet and when I got there she had his head into her mouth.. my mistake but I cant blame her or him for it..just my irresponsible care taking...I wil lnever do that again, thats why if I take them somewhere or bathe them I do it girls with girls and boys alone by themselves!!! thats the number one rule I go by : BOYS BY THEMSELVES..ALL THE TIME! Hope this helps