Equal Rights

I do not want to discuss whether gay marriage should be legal, if pro athletes should come out or anything like that. What I would like to discuss is why do people say it is a matter of equal rights?

Everyone in the U.S. has the same right to marry. The restrictions apply to everyone equally. So why is it that the pro-gay marriage crowd keeps using equal rights?

Straight people have the right to marry who they want, those that they are attracted to. Gay people do not have that right.