First, I struggled to find a mattress to fit properly. I didnt try a twin xl,that may have fit better. I got this to use as a cuddle couch (aka lazy day couch) for my living room bc it seems that most sofas have no space to curl up on anymore! (Unless you can shell out tons of ). Aside from the gap between the mattress  the arm, my other issue was,trying to make it appear more sofa like. When I finally resolved myself to a few throw pillows and a large blanket, it became the go to sit around for myself and my boys. Now, we did not rough house, there was no inappropriate behavior happening here,but the corner of this thing busted three  a half months after using it as a couch (every day sitting). I suppose you get what you pay for, but, I simply would like to give a heads up where I can. On the main bed a twin is not gonna do it  its not ok for every day.