Fingering anal

I understand there is and always will be this urge to want to try something new in the bedroom every once in awhile. Who has had someone slip their finger inside their anal and does it ever get less painful over time?

My man is wanting to try anal sex but I have told him that is absolutely a no enter zone. I do believe he is trying to get my anal more flexible for the size of himself. I mean he did begin with his pinky and I love it for the most part it's just the in and out that hurts. Any suggestions .....