Can you get an STI if you have sex but your partner doesn’t cum inside of you?
Yes, it’s possible to get a sexually transmitted infection even if your partner doesn’t ejaculate inside your vagina. STDs can be transmitted through semen, but there are a lot of other ways they can be spread, including contact with vaginal fluid, pre-cum, open cuts or sores, and skin-to-skin contact. This makes the withdrawal method a pretty ineffective way to prevent many STDs.
Condoms are a really good way to prevent transmission of STDs. Just be sure to use a condom for the entire time you have sex — which means putting it on right before you start having sex, and then taking it off after ejaculation. Condoms are much less effective if you don’t use them for the entire duration of sex. Read more about STDs here.