I have three total 1x1's going on. Two of which is going great and the other one is just going slow, but good. I've had three other 1x1 start and just end suddenly. One seemed to fizzle out for no reason and the other two got about 4 posts in and I never heard back from my partner. 
Has anyone else had this happen? I don't think it's me because my other 1x1's are going good, but I could be wrong. Is there a good way to tell if you're going to click with someone on a 1x1 early on or is it just a wait and see thing?