I have been trying to introduce the wife to bum play over the last year or so. I have managed to get a well lubed finger inside her a few times, although an inch at most.
When I am down on her and do this she does seem to cum quickly but instantly pushes my finger out again. I have bought a beginners butt plug and another small anal toy which she slipped in one night while drunk, but took it out again a few mi ites later. Last week I put her on her knees and licked her ass for a while and she didn't stop me although as soon as I tried to push (a well lubed) finger into her she stopped me.
It's not really something we have discussed much although in bed I did ask her if she wanted to use the butt plug but she said it was disgusting and that we tried it before and it didn't work
Any advice on how to move forward greatly appreciated