Q:

What is the function of 而 and 為咗 in 我哋為咗決定去邊度度蜜月而閙交 in Cantonese?

我哋為咗決定去邊度度蜜月而閙交.

In this sentence, I understand that the meaning is “we got into an argument when deciding where to go for a honeymoon.”
What is the function of 而 and 為咗？

A:

[為咗 A 而 B] = [ to B for A]. It is a two parts function word for  "for "
[(為咗) cause (而) verb]  =  [verb (for) cause] 
Example :
"(為咗)钱(而)工作" =  "work (for) money" 

[我哋(為咗)決定去邊度度蜜月(而)閙交] =  [we (to) quarrel (for) deciding where to go to have honeymoon] 

In English, we have to omit "to" before the verb if there's a subject in the sentence , e.g. "to work for money" -->  "I work for money". but we don't omit "而" in "我為咗钱而工作" in Chinese, because [為咗 cause 而 verb] is a set structure.

