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However, my guess is that you are seeing him Rumblestrutting - making a vibrating/rumbling sound and wiggling his bottom.
If so then that is an entirely normal display of dominance and boarly behaviour. It is something he will do his whole life. It does not mean he isn’t happy, in fact it’s the opposite, he will very happy if he has a new girlfriend! It is something he will do to show off to a new companion (and boars do it whether their companion is male or female)
A - Z of Guinea Pig Behaviours
How long were they together for speed dating at the bonding centre?
Have you put them back on neutral territory now you have them at home? Or have you put them straight into what is his cage?
We advise that piggies who have gone speed dating (so were only together for a short time before coming home) are put back in neutral territory when you get home. There should not be any hides in the bonding pen.
This is because speed dating usually does not give them chance to get through enough of the bonding stages, it only gives them chance to accept each other. They need many more hours to go through the dominance stages of bonding.
Once they have been together for several hours/even overnight at home in neutral territory, then you move them back to the permanent cage and add hides.
Do also be aware that changing environment will cause new rounds of dominance. So even if they were settled at the bonding place, now they’ve come home the dominance starts all over again.
If you have put them straight into the main cage then that is ok given they’re already in there. Dont move them.
Did you thoroughly clean the cage out first so that it doesn’t smell of just spice?
Do be aware that it takes two weeks after bonding day for them to fully finalise the details of their relationship.
If you have only just brought the new piggy home then she will be scared so needs time to settle. Cover part of the cage with a blanket so she can feel more secure but make sure you can still monitor their interactions given they are still very much in early bonding stages
Bonding and Interaction: Illustrated Bonding Dynamics and Behaviours