Jon and Zeke would use mày-tao, refer to the other as "người yêu" or "bạn trai" (lover & boyfriend). Sometimes Jon hides it by refer as "bestie" or "friend", and Zeke just says he "was a dude". Jon's official pet name is "mon cher". He will not use a pet name in english, thank you very much. Nonetheless, Zeke's was a different ballpark. The pet names varied from: darling, honey, to sunshine, monsieur (though Zeke disaproved Jon's pronunciation several times), boo and bro.
Titus would call Shane "anh", as Shane would refer to himself as "tôi" (ikr). Shane secretly loves it when Titus refer them as lovers, but srsly, admit that they're dating is fine.
You wouldn't notice, but Lloyd's pet name is "love". Lloyd will refer to Yuune as "the hubby", and "Yuu-chan" when talking in Japanese.
Thales and Chev use "my fiance" to talk about one another, and "darling" to each other. Chev might use some French, yet most of the time they would just use others name.
I will not ask Hanji, even for the purpose of this article.