I have a similar issue sometimes: I decide for a scheme, enjoy painting it for a while, but at some point I start looking through blogs,
WD issues, or the dakka gallery, and another scheme grabs my attention so I suddenly want to paint that one.
So basically it isn't that I was bored with the first scheme, but I get hooked on another one. I mostly do continue to paint the initial scheme, I just allow myself to do a one-off miniature in a different one from time to time.
Okay, now upon rereading that for spell-check, I realise I could easily rephrase that a bit:
I have a similar issue sometimes: I decide for a girl, enjoy spending time with her a while, but at some point I start looking through the web, a nightclub, or just somewhere on the street, and another girl grabs my attention so I suddenly want to spend time with that one.
So basically it isn't that I was bored with the first girl, but I get hooked on another one. I mostly do continue to spend time with the first girl, I just allow myself to have a one-off evening with a different girl from time to time.
Okay, so this second part isn't really true, I just realised it was funny.