I understand. Unfortunately you have to decide whether it's more meaningful to be the "nice guy" and not take the job just in case your FOL comes through, or do what is best for you at this moment in time and take the job and, if required, quit during the job.
I'm in a similar situation where I am currently doing an internship which will likely end with a job offer (assuming I'm as good as I think I am) in the first week of August. I'm also waiting for my Tier 2 eval to be looked at and approved/denied (2 months waiting already) and would hate to accept a position with my current company and leave within a couple months for a job that I applied to 2 years ago now.