I have stormed out angrily several (many?) times. I have had all the intentions to leave but never been able to.

When I stormed out the first time and was just standing/waiting behind the door, I heard the T packing up his stuff and preparing to leave (I was the last session before his lunch) through the other door. Then I just stormed back in and inquired where he thought he was going during my session time. Next time he already knew that I was probably coming back in. I think the longest it has taken me to go back in was ca 5 minutes. Not that things were immediately calm then and few times I managed him to beg me to come back in, too.

Now when I think about it, it hasn't happened for a while - maybe a year? Nowadays I'm able to say when I have the feeling of leaving and instead of acting out we can actually talk about it.