When having sex, the fluids in the vagina start drying up why does it glue up?

Many possib: It is likely that seminal fluid causes that consistency on the vaginal secretions. Orherwise glue-like vaginal secretions could mean inflammation/infection especially yelowish color and more if there is itching, increased secretions, or bad odor. Other possibilities is reaction to lubricants or to condoms. Vaginal dryness is common in the preovulatory phase, and postmenopausal years.