In Japan most couples (not married) split the bill.
The most common type is when the boyfriend pays 60-70 percents of the bill and the girlfriend pays the rest. Or it can be totally half.
However on the first date, guys tend to pay all of the bill if he likes the girl.
He does this so that he can say “You can pay next time” and get another date.
Of course it depends on the person, financial situation, or the age.
For instance, when my friend was still a student, her boyfriend who already was