The fact he's been screwing around with one of his subordinates is of little importance in itself, especially given the extraordinarily lax attitude Brits now have towards infidelity (our Prime Minister is the most notorious philanderer in parliament, a man with an unknown number of children from his serial cheating).
However there are still some important issues to consider.
First, there's no public record of Gina Coladangelo's appointment as a Department of Health adviser last year, and no evidence of a fair recruitment process having been undertaken. We know Gina Coladangelo is a long-term associate of Matt Hancock from their time at Oxford University, and it would be bad enough if he was just handing out jobs at the Department of Health to his chums, but it's a whole different level of corruption if she's his mistress too.
Coladangelo was previously a director at the lobbying firm Luther Pendragon, which boasts that it can help clients “navigate and influence complex legislation”.
How much influence at the Department of Health have this lobbying firm had since her appointment?
Have this lobbying firm received any of the £billions in untendered contracts Hancock has been lavishing on Tory donors, corporate spivs, dormant shell companies, blatant tax-dodging schemes, his sister's firm, and even his former pub landlord?
Matt Hancock has overseen a terrible response to the coronavirus crisis, which resulted in tens of thousands of needless deaths (especially as a result of the insane policy of sending infected patients back into care homes full of the most vulnerable people of all); he's been slammed in the courts for all the dodgy untendered contracts he's been handing out, and for lawlessly hiding the details from public scrutiny; he's been derided as useless by Boris Johnson (who has inexplicably allowed him to stay in his job); and now he's got serious questions to answer about the numerous conflicts of interest his extramarital affair has brought to the surface.
It would be absolutely ludicrous for Hancock to get sacked for his infidelity by a serial philanderer like Boris Johnson, but all the dodgy contracts, needless deaths, and blatant conflicts of interest should easily be enough for him to lose his job and be forced to retire from public life, at an absolute minimum.
It's just that Britain now seems to have the same lax attitude to corruption and conflicts of interest as it does to infidelity.
Once a nation allows standards in public life to collapse into the sewer so badly that a bone-idle, bigoted, elitist, philandering, inveterate liar like Johnson can become Prime Minister, it becomes difficult to see how anyone will ever actually get held to account for anything.