What should I say at immigration regarding my purpose of visit when returning to Thailand for marriage?

Hello everyone, a small follow-up from my post 4 days ago.

Thank you this amazing group for helping me to avoid overstay because of incorrect information. (Thank you university)

I’ve visited my Immigration (Chaegnwattana) where a very kind old lady helped me to cancel my student visa and confirmed that I should fly out as there is not enough time for me to get married and start the process of non-Im O visa.

I’m flying out to Cambodia this Saturday morning and coming back on Monday. I have a few more questions.

I’m flying with my Fiancé if this makes any difference and the airport is Suvarnabhumi Airport.

In my passport I only have extensions of stay based on studying in University for bachelor’s degree and visa cancellation stamp.

I’m going to get 30 day visa exception stamp.

What I’ve prepared:

A ticket out of Thailand

20.000 Baht

Thai pass (in progress)

In addition

I have a letter from my fiancé stating that he asks me to come to get married with his address, ID card number, date and signature. ( someone has suggested that on my previous post, thank you )

The question is if I’m asked by immigration at the airport :

- Purpose of visit ?

What should I reply? As I understand the latter from my fiancé is an additional paper that I’ll show as evidence only if asked.

Should I reply that I’m here to get married and process my documents or not?

I’m very confused, I have no experience in this kind of situations. I always had my long term Student visa and entered with no questions.

Again thank you.