Language partners...where are they now?
Everyone is busy with their life. Spending for some Finding the time to have a conversation with language partners seems quite difficult and sometimes, even (or downright) impossible. The other reason is due to the different time zones or perhaps they are simply not interested anymore.
If you're guessing about the time zones then use "It could be due...." if you're not just guessing, then it's okay to use the word "is."