Common-Objective-869's journey

I just received an email from my casual contract job informing me that they are terminating my contract. This is my first job ever, and I'm feeling confused and worried about the situation. The last time I worked was on April 18th, which means I haven't worked for them in over three months. I had been keeping them updated about my availability, but it seems that wasn't enough. They want me to return my swipecard, which I plan to do, but I've also emailed them to ask for the reason behind the termination. I'm not sure if I'm allowed to ask this, but I feel like I need some clarity on what went wrong. I can't help but feel a bit ashamed about losing this opportunity.