I am dual citizen of US and CR (EU). Will travel to Bolivia, where US citizen has to pay $135 for visa while EU has free visa.

Based on my readings when checking in the US for the flight with destination Bolivia, I will show the airline my EU passport. (and when checking in Bolivia onto US headed flight I will present the airline with my US passport).

So here’s the catch, that I can not solve on my own When I used to have a green card, the airline always wanted to know how I will get back to the US, so upon the check in to travel OUT of the US, I had to show them the green card (and of course I had to show the green card upon boarding the US headed plane).

If I leave US on my EU passport and the airline asks me how do I plan to return back to the US, what do I do? Tell them I have two passports ?
Thank you.