BJ's often seem to be the first thing to disappear from an OH's repertoire in the bedroom. I'll never forget the first time I received a full OWO BJ to completion with CIM from a fit, young Polish SP. It was the first time for me in God knows how many years and she left me a quivering wreck on the bed whilst she went to the bathroom to spit. 
Early 50's for me.
Sex with the OH had become quite infrequent and although some effort at persuasion might occasionally deliver a half-hearted unenthusiastic and inexpert BJ, I had been explicitly told on numerous occasions over the years that CIM was definitely not permitted. Definitely not.
To partially 'scratch the itch' of the infrequent sex I had taken to visiting strip pubs to watch the 'pound in the pot' girls on stage, and occasionally taking advantage of a dance, although never thinking it represented good value for money at £10/£20 for three minutes of not an awful lot more.
However 'looking but not not doing' at the strip pubs probably made things worse and after sex with the OH had become even less frequent for a period, after some research here and elsewhere, I summoned up the courage to visit a local parlour with a girl who advertised CIM.
It wasn't the greatest punt in the world, but she delivered what was advertised. For an amount not significantly over several dances in the strip pubs, a pretty slim young twentysomething was happy to receive attention from me to her naked body that certainly would not have been been allowed during a 'dance' in the pub, and more importantly she was happy to be fucked and then end with an enthusiastic BJ and a CIM finish.
Since then sex with the OH has carried on in the same pattern, sometimes more frequent than others, and sometimes more enthusiastic than others, but always on her terms when she was prepared to grant it. The trouble was once that retail sex box was open... well let us say I was hooked and still cannot believe I wasted so many years not taking advantage of it.
A marvellous concept.
Now when I fancy sex (and proper sex doing things that the OH would throw me out of the house for if she even suspected I was thinking them) and not get back the usual 'not interested' or 'if you must' from the OH, I don't try to persuade her by taking her out for a meal or away for the weekend.
Instead I make a phone call and hand over that same amount (or usually far less) and instead of the usual frustration of rejection from the OH I am wondering how the day can get any better as I look down at the pretty face of the girl using her lips expertly to suck me off, and then it gets better as I find myself balls deep admiring the pert asshole of the size 6 twenty year old I am fucking doggy, and then it gets even better as she presents an open mouth for me to shoot my load before dribbling it over her pert tits.
Some punts are better than others but none have ever been as frustrating as thinking you might be lucky with sex at the end of a nice evening out, only for it to be snatched away as they are 'too tired'.
Then I can repeat tomorrow, next week, next month, whenever I fancy, with the same girl, a different girl, or two girls together, white, black, asian, slim, chubby, busty, flat chested, GFE, or PSE or whatever I fancy. Sometimes it has been a couple of times in a week. Sometimes a month or so apart. Sometimes six months.
But back I come and am just grateful there seems to be a never ending stream of pretty young things, who if they were a civvy would have ignored me when I was the same age as them (and me probably too scared to approach them) and now when I am decades older would just think I was a dirty old creep if I expressed any interest in them, have weighed up they would prefer fucking and sucking me for half an hour to earn the same that they would earn working a minimum wage job for 8 -10 hours. Consumer society at its peak.