I assumed that he was unwilling to eat due to breeding season.
I purchased him as a male, and had him double checked when I picked him up.
The female was purchased as a female, and I had her checked by a local breeder after bringing her home. (I don't trust myself to do it myself)
The thing that's really weird is that he doesn't flee until she tries to tailsnuggle him. Otherwise he doesn't have a problem with her - they do all the normal things you would think two snakes in a tank would do.
And really - he's not /that/ small - just compared to her he is.
I'll have them both re-checked tomorrow.
Icky did pass in November, and I saw no evidence of anything internal. He also hasn't lost more than 5g in the few months I've had him. He also had no evidence of anything else wrong - hence why I brought him out of quarantine.
I'm fairly concerned about him, so I'm glad to get a few responses on the matter. Thank you guys.