Husband in Thai
To say Husband in Thai it is either สามี (săa-mee) or ผัว pŭa.
สามี (săa-mee) is the more polite way of saying husband.
ผัว (pŭa) is more colloquial. Depending on the situation, if you say สามี (săa-mee) it might sound too formal.
If you are not sure which one to use, I recommend saying สามี (săa-mee) as it will never sound rude.
Wife in Thai
To say wife in Thai it is either ภรรยา (pan-rá-yaa) or เมีย mia.
ภรรยา (pan-rá-yaa) is the more polite way of saying wife.
เมีย mia is more colloquial. Depending on the situation, if you say ภรรยา (pan-rá-yaa) it might sound too formal.
If you are not sure which one to use, I recommend saying ภรรยา (pan-rá-yaa) as it will never sound rude.
Couple in Thai
If you want to talk about a couple in general you can use คู่รัก kôo rák. คู่รัก literally means (คู่ = couple) (รัก = love).