My girlfriend and i recently purchased a pair of beardies from a local pet store. they have been living together for 4 months and doing just fine. however, "my" beardie never seemed to grow whereas my girlfriend's exploded in size. we were sure to monitor their food intake so they had equal proportions. we also noticed recently some aggression issues between them and with the size difference, i feared it could do some damage if we let it go too long; so i separated them. now that they are apart, my girlfriends still seems to be growing, even more than before... and mine is still about 3.5" from nose to tail base. he also seems to be avoiding his food. Every time i take him out he also puffs up and opens his mouth at me. so, in order to get him to eat today. when he puffed up and opened his mouth, i would shove a cricket inside and he would eat it. but when left to his own devices, he would just let them crawl on him.
i am completely lost and don't know why he is acting like this.

Separation anxiety?

-Trevor