I am a guy and use butt plugs for solo stimulation quite frequently, never broached the subject with any partners.
I have been having a nagging problem for a long time. I like the "fullness" of butt plugs and it feels absolutely great when I'm hard and aroused. But when I am not at peak arousal it feels a bit uncomfortable.
I've tried various position.
When I am lying down on my belly - the but plug is very comfortable aroused or not.
Squatting on the floor - quite uncomfortable
Lying on my back or side with legs in front of my upper body - neutral.
I think the problem is with the fact that my rim just can't deal with objects in it and does tense up which causes pain for the rim. I have ordered the doc johnson mode butt plug which has the girth around the stem akin to a ladys index finger which is very small - it might do the trick. I have yet to receive it and play with it.
In any case is there any way to train the rim to not squeeze too hard and cause itself pain. Ideally I want to go onto a bigger butt plug equivalent to a 7" penis. I can;t do that if my rim is too tense.
I do warm up and gently lead up to it. Insertion is not paintful at all. Just after an hour or so it feels quite uncomfortable.