The inclusion of Katherine Jenkins was incredibly pointed given the rumours.
The Beckhams got so famous because he was a good footballer who looks gorgeous. Simple as. They've been canny, and managed their brand really well, but the public knows nothing about them at all. We barely ever see them talk outside very tightly controlled situations. I'm sure they can be nice on individual encounters but that's not the whole of them or their marriage. How many of us know a friend of a friend who had their mortgage paid off by the Beckhams for some favour? It's almost a fantasy of a good-looking rich couple and what they might do.
Same as most other famous people. We are handed an image; it's no different now to 1930s Hollywood, when gay actors were ladies' men, and illegitimate pregnancies were hidden. Social media gives the impression that we see the 'real' them, but that's nonsense.
Sometimes you get a critical mass of passing encounters that suggest the 'truth', good or bad, about a celebrity. Frequently the 'truth' about what they get up to (eg Beckham's affairs) is an open secret in certain circles, but the press won't cover it for a whole variety of reasons.
But it's amazing what the rich and good looking can get away with.