Is it appropriate to say
'Sorry for making this hard for you'?
Some context: We tried to set up a time to meet but we have conflicting schedules so we decided to meet later at night.
Perhaps, it's not that hard but just inconvenient. I think I'd say, "Sorry for the inconvenience." If you want something more original, you might want to try "Sorry we can't make it earlier. Thanks for agreeing to meet in the evening."
I presume that you do not wish to suggest that it is the other guy's fault. If you say it is hard for them, then potentially someone else would not find it so hard - so it is their fault!
So you must therefore imply that only you are to blame. One way of saying that would be to say "I am sorry to be so difficult..."