This is not a medical question, so I'm not sure where to ask it. Does a woman's vagina get "smaller", the longer she goes without sex? Can her male partner tell if she has had sex during their extended time apart? Can you tell how long a person has been sexually inactive, by their vagina? Thanks in advance!

No

Nope

Smaller due to abstinence? They're correct, it cannot happen. Pelvic floor muscles can be strengthened and muscle tone increased with exercises, but the size is what it is.