I read somewhere and then confirmed by rewatching -- Father Arnon is talking about Kongdech. Kongdech continued with seminary, which was about 10 years, which was the last time they saw each other. Then Kongdech took another 20 years before being ordained. I didn't read the novel, so not sure, but I read somewhere someone saying that Kongdech apparently went to do some volunteer work, so it took a little while before he did everything to become ordained.

thai_lovers_:

I thought this one was an original work of GMMTV, tho?

Was it based on novel?

it was an original work but gmmtv releases novels too after announcing their original series, tth novel was released before the series was aired

matchakkatt:

In the novel, it says they took time off after Tan confessed he is in a relationship with a man. So after their visit the motel scene, they actually came back to school to finish their exams. I think we can just assume that they came back somewhere around 2015 and saw each other lol

no actually someone else confirmed that father was actually talking about the person who was getting ordained, which they were trying to make us think it's tanrak, so when father said it's been twenty years he was talking about kongdech's journey to become a priest, becuase you would notice when they again come back to the present time in the last episode, the father was talking about the person getting ordained

idk should i delete this discussion if i have got my answer?