"There's a lot of research out there that suggests giving to others is good for the self," says lead study author Amy Muise, Ph.D., of the University of Toronto, and that effect is even stronger with a romantic partner. Plus, Muise says, knowing you can satisfy your partner's needs is a major confidence booster. 

But zeroing in on her desires at the exclusion of your own won't deliver the same outcome, says Muise. The solution: Aim for compromise. If you usually perform oral sex on her because she loves to incorporate it into foreplay, see if she's up for something you want, like shower sex or a morning quickie before work. That way you'll both feel accounted for, Muise says.