Mate's wife on holiday. Residential & quiet area.
Here's what I see, quiet residential street, mates wife on holiday, he's not, neighbours know this, any residential street has its cadre o f curtain twitchers, late afternoon, taxi draws up and sets down quietly but tastefully dressed fuckable lady, she looks around, obviously here for the first time, walks upto your mates front door (maybe the taxi takes off, maybe it sits and waits), someone lets her in the house, an hour later the reverse process takes place. Run forward a week or a month till the wife is back, talking to neighbours telling them about her holiday when one of the curtain twitchers says, oh who was that woman visiting your house the other week ?
Not a problem for the wg, maybe not a problem for you unless you got a wife / partner who is also mates with the wife, but could be deep do do time for your mate.