spoiler! disregard if your going to watch it!
nang'ek has only 200,000 (song san) in her bank account and the wedding cost 500,000 (ha san). Her boyfriend is in debt of 500,000; thus, he marries nang'ek to get her 200,000 baht.
nang'ek then borrow 200,000 more baht to help pay off her wedding. However, the money is from puri's parent which aom's dad had taken from puri's parents. Because aom had taken 200,000 from her dad, aom is in another situation which she might have to marry puri. Her sister (is it jakjaan? cus it looks like her) likes Puri and is mad that her dad gave the money to Aom.
yep. i just wanted to clarify the correct of money nang'ek has. haha.