Can I ask to only do morning shift?

I work as a cleaner. I finish early. We have lunch for 2 hours at 11:30 but I finish way before. I am very through with my cleaning and don’t slack at all its just that there is truly nothing to clean. I handle 6 rooms the 2 biggest are only used once a week. 2 rooms are so small i dust sweep mop take out trash in 50 minutes tops. 25 minutes each. 1 room is big but theres no mess at all. My room “office” is small too i finish in 15. They are a construction company i clean the offices of the engineers and the project is just starting so there are barely any furniture or people to clean up after. I also live in a tropical country and the other day it was 51c. I don’t clean from 11 til 4 because it gets too hot and again there is nothing to clean because i cleaned in the morning.
Even the “boss”’s office gets only cleaned once in thw morning because he goes home too early or just doesnt want me cleaning in the afternoon at all.

Im incredibly grateful for this job. But i have an LDR SO
coming to my country for a month to which i negotiated for them to only do 2 weeks tops. Im new so asking for a leave is not a good look at all and i think not possible as well.
I do not mind getting less pay, i get paid hourly.