An uninfected individual has about a 75% chance of contracting herpes during intimate contact with someone already infected.
Not having visible sores, and other symptoms of genital herpes doesn't exclude the possibility of being infected.
Genital herpes virus is transmitted by close oral, anal, or genital contact, including intercourse, masturbation, kissing, or any direct skin-to-skin contact.
A person can be infected and still not showing symptoms, and can be infective for others when sores are present, sores are healing and when there aren't any sores (even without sores the person potentially always is shedding active virus).
Performing risky sexual activities without protection and with people without known STD status is not a good idea.

Herpes is a tricky virus. It is not shedding from an infected person all the time, but it does shed without sores about 4% of the time if the individual is not using protection or antiviral medication. So if you have unprotected sex with a person who has herpes, your chances of getting the virus run around 4% at any given time. If you have sex during this 4%, your chances of contracting it are very high. You said you contracted it but your boyfriend didn't. It is possible that your boyfriend already had herpes and didn't know it and that you contracted it from him. Most people who have herpes don't know they have it - some don't have symptoms and some have such minor symptoms they don't recognize it. It's also possible your boyfriend DID contract it but isn't showing symptoms. Not everybody shows symptoms. Some people can have the virus for years without ever having an outbreak. The best way to test for herpes is to do the IGG blood test 3 months after suspected exposure, after the body has had enough time to make antibodies. Or your and your boyfriend could have the blood test done right now, to find out if either of you already had the virus. 1 in 4 women and 1 in 5 men have genital herpes and most don't realize they have it. When you go for STD screening, they generally do NOT include the herpes test even if you ask for all STDS. YOu have to specifically request it.

It is also possible for someone to come into contact with the active herpes virus and not contract it. There is no known reason for this but it does happen. Sometimes people may have herpes already in the form of the other type, type 1 vs. type 2, and although having one type does not offer complete protection agaist contracting the other type, it is possible to get some protection and antibody activity against a new strain.