Same here, I have always had spells of boredom with my interests.
It's strange because I will get so frustrated with an interest I just lose all interest in it completely, yet I can still remember that yesterday there was nothing more important.
To be honest I'd always put this down to depression (before I found out about AS and did all my research) so if it is because of Autism then I guess depression could still of been a factor.
Art has always been an interest of mine in various forms but I did used to be into drawing big time, but my interest wained because I'd get frustrated that I was never satisfied with my work. It was never how it was in my head.
Now I'm thinking about it, frustration seems to be the common denominator between losing interest. Most of the time I regain interest in my activities and have a renewed love for it, and most of the time I have gotten better at it due to having a break - like I've levelled up
im wondering if a dip in my mental health can explain frustration too.