Have you both been tested for STDs? Are you both clean? Are you in a long-term / committed relationship? If yes to all three then it would be safe to not use condoms as there would be no risk to either of you. However, if this is a new relationship or you or her are also sleeping with other people, or if you haven't been tested negative for STDs, then you must use them. Not to mention condoms provide a physical barrier to pregnancy which could be useful in case the pill fails.