I think the differences in what people expect can be massive.
ExH and I were together from 19 - 36, so through end of uni, training in professional jobs, having kids, me being part time.
Our earnings improved but I don't think our lifestyle did massively - we had nicer holidays and cars but I still reviewed daily spending etc.
We split up, our kids were 5 & 2, I was working part time.
I was by no means on the breadline, my part time was in a professional job, ExH paid child maint, and most importantly with regards to my standard of living I didn't have any housing cost, nor significant childcare costs.
We had a good lifestyle, a UK short break and a summer break in europe, a decent car, the kids did activities, I saved and made pension contributions.
I fully appreciate that the ability to do this was mainly due to the low housing & childcare costs - and that these are a killer for most people.
But I also kept my everyday costs low.
I took the kids to the cinema - but we did kids club and took snacks & drinks with us.
I always shop around for utilities & insurance, buy with quidco,
We eat relatively cheaply (mainly because I'm not a foodie).
The kids do activities but they aren't that expensive - judo is £1 a week plus £21 annual licence, jogging club is £70pa each, scouts was the most expensive at £40 per term.
I had National Trust membership and we go to local properties for walks & take snacks and drinks.
I had a smartphone but I've always brought outright and then have low contract costs, currently ds1 & I are both on £5pm and dd2 has a free SIM deal with my broadband provider.
I drive a nice car, I brought it 2nd hand but only 6 months old. But now it's over 6 years old and I expect to keep it for another few years as long as nothing serious goes wrong with it.
A few years later I got together with late-DH, he earned significantly more than me but probably not than ExH had been earning until just a few years before we got together.
But his lifestyle expectations were poles apart, Waitrose v Aldi. And tellingly I think not even realising that choice was an expensive one.
Along with all the other choices - full fat sky, new cars, expensive pets and hobbies, always new phones etc. Never taking drinks & snacks places and then buying them while out.
I think it is easy if those are the circles you move in to assume that it's normal, and even more so if your circles are higher income than you.
Late-DH was amazed (literally) the first time we went to an Aldi at the cost of things like fruit & veg. I (now) appreciate that Waitrose has some lovely stuff, but a cauliflower is a cauliower.
Late-DH and I, as a household, spent more than I had done previously, but nothing like what he had done previously in his 1st marriage.
I do think it is very easy to think that things are just normal when actually there is a lot of discretionary spend.
It seems that maybe this thread has opened your eyes to that OP.
But it is also important not to take it too far, there is no joy in a life on the breadine nor in replicating it if you don't have to.
As an aside OP, you don't mention what your pension provision is, but £30 if thats all you have between you (no enhanced employer schemes) is seriously inadequate. I really would be looking at that.
Finally, how long had you been paying that boiler maintenance? £24pm is £300pa, less say £70 for an annual service. 4 years of that has covered your £900 claim. I'm not saying it isn't worthwhile, but you do need to look at the whole picture.
Then again it would be sods law that you ceased it next week and in the new year needed a major claim!