Just tell him that, if he's hurting you, there's a good chance he will tear the frenulum on his penis and it will hurt him a lot more.
As everyone has already mentioned, slowly, slowly, slowly. Fingers are definitely the first thing to try - either yours or your partners. The initial entry is past a very tight ring of muscle but once that has been breached everything becomes a lot more comfortable. I LOVE anal play but hubby has just decided to try it. Once he was enjoying a finger we purchased a small beginners butt plug which he now really enjoys. Make sure you buy a soft plug to start with - don't be tempted to go for metal or glass, for example, until you're really enjoying it as these can be a bit intimidating.
We just use LH water based flavoured lube and that makes things glide really nicely.
Baby wipes are good for a careful wipe round beforehand - just to make sure everything is nice and clean.
Definitely a winner here.....never wanted to do it in my youth( social hangups about it were stronger then... Now it has become more acceptable and fun to experiment with)
Take your time....and certainly do not go in guns blazing....get really seriously aroused.... And when you think you are ready... Lube..and work from a single finger or slender butt plug...and get used to it first...then build up...remember he can't go in hard and fast.. It is slow and firm...and stop and wait to get used to him there...and then move a bit more.
If worried about the hygiene issue...you can get a douche( kneeling down in the shower with bum in the air is the best position I found to do that!).. And or eat light in the run up to expecting a spot of exploring.
On my first time...I had an idea it might get put on the cards..and I hardly ate a thing all day! Nervous energy... 😄
Take charge of the pace... And enjoy the moment... Xx
It is if h use a lot of lube and go very slow