My ex-girlfriend and I both tried to do anal stuff upon each other so I have some experience with this,

Make sure you have lots of lubrication, first off.

Take it slowly... Lots of foreplay beforehand might help your body relax.

Have you and your partner agree on a "safe word" at which point he will stop if the pain becomes too much to bear. There will more than likely be some pain the first few times, especially getting past that barrier of him actually getting in. It will hurt but in my experience it subsides once that is gone past.

If you can't get him in, don't feel bad. Take your time.. Let him use fingers and toys on you for a while to help loosen you up. Perhaps even invest in a butt plug to help stretch you a little bit it might help..

Most importantly, dont rush it. If you fail the first few times b/c of pain... Don't get too upset.. it takes a little time to make it be comfortable enough to fully take anything back there and truly enjoy it.

I'm not sure if that helps you any. Just what I know about the problem.

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Wow... Funny isn't it? How you think Love has finally found you..... But at a whim it withers and blows away...