Wow - She loves his black cock........, she probably had it before........, look at her belly 4:45-5:30 and again after 7:30...., and after 8:30...., she may already be knocked up......., a lovely naughty wife bringing home a creampie and a little surprise....!
She is holding back because hubby is present. Either that, or she has suffered years of being fucked badly, and doesnt realise that she is supposed to enjoy it.