ask her if shes ever tried it.... no matter the answer, wait a few weeks, and while having sex (preferably in spoon position) just rub ur finger over it. (make sure tto get some of her juices on ur finger first)

if ur givin it to her good, it will only give her pleasure, no real pressure at first, jsut to give it some nerve attention. (if shes totally against it, u can play it off as a mistake and be done)

then u rub it a little, not in, jsut rubbing the opening.

stop there.

not everytime, but every other few times having sex, give her that treatment (lets her get used to that area being touched, lets her know it makes her feeel good, gets her mentally prepared, lets her know u have an interest.

after a while, when the finger touches it, you get the "invite" she will moan or push against ur finger.

at this point, u start to put finger in a lil (middle) very slowly.

same thing, do that every few times u have sex.

soon she will be practically "begging" for it. pushing against ur finger, moaning as u are in both holes.

im serious. works everytime.