If the partner is not treated, the woman may get PID again, especially if condoms are not used while having intercourse. You should get medical care immediately. PID is a serious disease that requires immediate care. Furthermore, other serious conditions need to be ruled out. You should avoid having sex while you have symptoms since most cases of PID are caused by STDs.
Abstinence is the only sure way to avoid STDs.
Try to limit your exposure to STDs. Unprotected sexual activity increases your chance of exposure and infection. Use barrier protection, like a condom. Look at your partner before having sex. If you see any sign of an infection such as rashes, sores, discharge or swelling, stop and talk about the importance of checking for an STD before having sex.