Hmm. In my opinion, and this is only mine hun so not gospel, she is looking to be too dominant for him.
She is the one instigating all the tiffs - he's just trying to get out the way bless him. I have to say when I bonded mine I never had the female acting this way - Cherry just allowed herself to be humped and humped til she told Dodge to leg it, he said ah ok I'm tired now, and they went to sleep together. The other lot just kinda said 'oh hi, nice to meet you, carrot?' not even any humping!
If it were me, personally, I would first of all chuck loads more in there to occupy them - I used two kids stools and a wooden arch with mine, loads of piles of hay, two foods bowls, and bits of veg all over the place. If there is more than just themselves to focus on this helps.
I would also disregard what age they are and pick your most calm girl, as this lady looks quite dominant and littly (sorry forgotten his name!) seems very 'oh crap Mum help!'
But as I say this is just me, I am not the expert, just going on what I have experienced
Good luck x