If a female has unprotected sex with guy a who has chlamydia. weeks later had sex with guy b. but guy b was tested negative. possible?

Russian roulet: Not everybody exposed to chlamydia will get the disease. More worrisome is that most people who do have chlamydia do not have symptoms. Therefore they don't get tested and can spread the disease unknowingly. That is why chlamydia is the sexually transmitted disease.

Chalmydia: Yes. Did the female test positive for chlamydia? was she treated? Also not every time you are exposed to a bacteria/germ do you get infected ,so female may have been lucky and not have gotten infected. ( just like if someone is coughing in a room not everyone gets sick). But don't count on luck use condoms