In my case it is definitely a bit of a mid-life crisis.
45, married for 15 yrs, happily but sex is not as often or as kinky as I'd like.
Did some exploratory punting in my 20s then settled down.
Started to visit pro-dommes for BDSM stuff after a while when it became clear that wasn't going to happen at home - but never felt the need (though occasionally tempted) to go for a vanilla punt.
A few months ago the urge came and I succumbed after a few pints one night in a Soho walk-up (Mary at 52 Greek St by the way)- it felt amazing, like a huge relief and release in every sense of the word. Had a few days of guilt and anxiety but learned to handle it - I've learned to be very good at covering my tracks though my biggest fear is still picking up an STD so I am ultra cautious about that (tend to avoid OWO eg).
Since then I've tried the whole range from 10 min walk-up quickies to an hour of GFE with a few kinks. Feels great - and very much like a mid-life splurge; my biggest worry is getting addicted and blowing shedloads of money which should be going to the family, so I'm thinking about imposing a strict limit (say once or twice a month) - recently it's just been a case of whenever I can (twice this week!) which I can't sustain.
I don't suppose I'll ever stop but if I could get it out of my system with a bit of uninhibited shagging now then perhaps I could settle down to the occasional favourite girl every month or so after a while...we'll see!
I do feel much happier and more relaxed, and my relationship with wife and family has definitely improved. I'm not going to be writing in to any agony aunts recommending it though - one to work out for yourselves, chaps
Anyway that's my 2p-worth!