The bitch came to us at day 10 of her cycle 3 days ago and has been everyday since. Both dogs were displaying all the right things. Him nudging, mounting  and licking her. her twitching and presenting her lady parts, even bending for him at one point.  And all this happened for the full time they were together on the first day and for 10 minutes on the 2nd day then everything stopped, now they just sit side by side looking at us? We had left them alone on the 2nd day whilst all was going good so not sure if anything had happened as when I checked hed mounted her but there was no tie to say it was a definate.

I understand  he's a first timer... but why stop?

I suggest you find somebody in your breed who is experienced in handling matings.   I had a mentor who we used pretty much all the time, meeting up at her place with the owner of the bitch.   She could mate chairs to tables - and mine is NOT an easy breed to mate, most needing assistance which means having the bitch across our lap and getting the dog to mount and then 'guide' him in.  We gave her a percentage of the stud fee for her help.   I think she quite enjoyed the visits!! 

NEVER leave them alone - somebody MUST be there to restrain the bitch who, if a maiden bitch, can often panic when the dog gets going.  And it would have helped had you known whether there was penetration, or not.  Slip ties can be successful (pregnancy).

I think you need to run a progesterone test on the bitch ASAP to see where she is and whether she has ovulated yet.  Go to your vet and get them to run a progesterone test.  You will probably get results the afternoon of the next day. 

It may be that you were too late - day 10 could easily be too late for some bitches.  Without running progesterone, you have no way of knowing what's happening.

> but why stop?

Most likely because she isn't ready yet.  Initial interest is because it was a bitch in season.  she may be a tart and teasing him but not yet fertile.

Is the bitch proven, when was she mated last time?  If a maiden, often bitches take after their mothers, when was her mother ready for mating.

I have had bitches mainly ready days 15 - 18, but I have  mother and daughter who are ready days 18 - 22.

This can be quite breed dependent, and then individuals vary.

I used a maiden dog on my most recent litter, the bitch allowed mating from day 16 to 20, but in fact whelped to the mating on day 19.

> The bitch came to us at day 10 of her cycle 3 days ago and has been everyday since.

Are you sure its is day 10? How experienced are the bitches owners to know she hadn't started before?
So today is 'potentially' day 13 which could well still be too early.
I totally agree they shouldn't be left without you supervising, you & the bitches owner need to know if he has done anything or not.