As of the time of publication, it is becoming increasingly possible to get health insurance coverage for a boyfriend in the United States. More employers are offering same-sex couples and opposite-sex partners benefits in response to a major Supreme Court decision in the U.S. versus Windsor case in June 2013, which overturned part of the Defense of Marriage Act.
Data on Benefits
An August 2013 study by the ERISA Industry Committee showed that 87 percent of large employers offered same-sex domestic partner benefits, and 55 percent offered opposite-sex partner benefits. The reason it was more possible at the time of this study to get coverage for a boyfriend if you were a male is that employers recognized that opposite-sex partners had an easier path to marriage. Other employers indicated plans to offer benefits for both same-sex and opposite-sex partners in the future.
Adding your boyfriend of three months to your plan is unlikely. You must register as domestic partners in your state. There is a huge variance in requirements for partnership by state, and laws are in flux based on U.S. versus Windsor. For example, the California Secretary of State website indicates that at least one person in an opposite-sex domestic partnership must be at least 62 years old. The couple must live together and share expenses. By these standards, it is difficult for the bulk of workers to register as opposite-sex domestic partners.