While having sex, we see a thick white paste on his penis. no itching, irritation&odorless.pregnancy test(home) is negative.period missed by 10 days, ?

Yeast or smegma: If he's not circumcised, the paste is likely smegma which is a cheesy collection of dead cells, skin bacteria and glandular secretions. He needs to fully pull back his foreskin daily and wash out the stuff. It's less likely yeast since it's not itchy or irritating.

Neg pregnancy test: Reasons for missed /late periods: low body weight, obesity, marked weight gain or loss, over-exercise such as in endurance athletes, breast-feeding, stress, illness, eating disorders (bulimia or anorexia), travel, hormone irregularities, drug use, medications (i.e., birth control) or med problem (polycystic ovary syndrome or Asherman’s syndrome. #1 reason is pregnancy.