Learn English – A word for knowing the truth but not wanting to believe it

Maybe it could be "likewise". It can be used in many cases, when someone expresses some feeling/opinion, and you want do say that you feel/think the same.

E.g.: A: It was a pleasure talking to you. B: Likewise. (it was a pleasure for me as well)

A: I feel sad for this. B: Likewise. (I feel sad too)

Etc.

The right word choice depends as much on connotation as definition. You're inviting someone to converse, and your invitation is being declined. I get the idea that you feel you're being rebuffed, and you want a word to describe the mostly monosyllabic responses you get in that light.

"Curt" comes to mind. It strongly connotes discourtesy. "Brusque" is a similar word, with similar connotations. Neither of those words is especially popular, but not to the point that I would shy away from using them in everyday speaking or writing.

"Reticent" has no connotation of discourtesy. It gives the connotation that the speaker's shortness has more to do with the speaker's mood or personality, and nothing to do with you or how you're being treated.

Terms like "tight-lipped" and "closed-mouthed" are synonymous with "reticent," but they are often used in the context of secrets. They imply that information is being withheld. Although neither of them implies discourtesy, they are often used to convey a certain a certain mild disappointment on the part of the person who desires the information.