Which one is better? When can we meet? When will we be able to meet?
I have a friend who can't meet up for about 3-4 years. because we live in another country each other.
In this situation,

which one is better?
When can we meet? or when will be able to meet? or do you recommend any good expressions?

Question

Which one is better? When can we meet? When will we be able to meet?
I have a friend who can't meet up for about 3-4 years. because we live in another country each other.
In this situation,

which one is better?
When can we meet? or when will be able to meet? or do you recommend any good expressions?

Answer

When can we meet? <-- this makes it sound like you are close by and are thinking of meeting up soon.
When will we be able to meet?

Answer

When can we meet? = What's our best and soonest opportunity to meet?

When will we be able to meet? = When will our situations and circumstances allow a meeting?