If you want my strict opinion, I think it’s a poor decision to choose to wait. There is a lot about yourself, sexually, that you simply aren’t going to know until you’ve experienced it, and that knowledge is going to affect your relationship with your partner or partners. Neither will waiting until marriage ensure that this will be your only partner. You can’t divorce-proof your relationship by waiting, nor does having sex before marriage (or engagement, for that matter) doom things. Plus: waiting until after your break-up requires lawyers is a bad time to find out that the two of you don’t sync sexually.