I am a graduate student who started to collaborate with a postdoc last year on a research project which we both came up with. During the past year we had several discussions about this project. I mostly did the calculations and proofs and he focused more on giving general advice and comments on the big picture of this project. The collaboration seemed to go well.
Early this year we decided that the results are strong enough and we should write a paper soon. I finished a paper draft containing all results about three months ago. There are still several sections (e.g. introduction) left blank because he insisted on writing that himself.
After I sent him the draft, he didn't start to write his part but asked me to change the structure of the paper and I also finished that pretty soon. Then he had a vacation for two weeks and I didn't bother him during that time. Every time I asked him about the progress, he was either busy finding a job or having a family emergency and he didn't start to write his part until now. He said once at a time that he could finish the paper in two weeks but then two weeks later nothing was written down.
I didn't want to rush him because job/family seem to be more important things than writing a paper, but I couldn't help but worry if he was just making excuses to procrastinate. And since he seldom wrote anything down from the beginning of this project, I have no idea how long it will take him to finish the paper.
How do I deal with the current situation? I don't have a high expectation that the paper can be finished soon, but I also cannot stand waiting forever.