Following on from Xantippe’s last post, I think many people’s expectations (at least in the West) of quality of life have changed both in terms of what constitutes ‘quality’ and how much of it they are entitled to expect.
What I mean is that for many people, the faith that they were baptised into (whatever denomination) is seen more as a ‘tradition’ than something that actually provides any moral compass. One consequence of this is that ‘quality of life’ is very detached from any sort of ‘quality of spiritual life’ and measured in material wealth and signs of ‘doing well’ like more holidays to more expensive locations, better cars etc.
People’s expectations and sense of entitlement also seem to have changed, at least among my peer group (I’m 44) I have several friends who maintain they can’t afford to have any more children when actually, compared to many families, they are very well off indeed. What they mean is that more children would lead to them losing the lifestyle that they feel they are entitled to because of the years of hard work they have put in from high school upwards.
I wonder sometimes if women who are my age were just pushed too hard at school into putting career before all else until the trappings of a successful career were seen the only ‘real’ badge of self-worth and achievement? Very few of my friends married before the age of 35 and fewer still before 30. Of those who did, I know just 1 who chose to be a SAHM and ironically, she and her husband genuinely do struggle to make ends meet, but they have the happiest, most well-adjusted children you could wish to meet. They don’t live in a ‘good’ area, or have lots of gadgets and fancy holidays. In fact, their lifestyle would be regared by many of my other friends as ‘unacceptable’ for them. For me, she’s the friend whose wisdom and faith I admire the most!
Against this sort of background, I can see why ABC becomes a habit. I know a lot of women my age who were very pious at school, but by the time we all reached university, having a sexual relationship with one’s boyfriend was considered ‘the norm’ and, as Xantippe has already pointed out, some people do wrong with genuinely good intentions. In the cases of many of my friends, they knew on some level that sex outside marriage was wrong, but they also desperately wanted to avoid creating a new life when they didn’t feel emotionally of financially ready to care for him / her and did not want to disappoint their parents. I’m in no way condoning their actions but I do understand them.
This mentality allowes women to go on contracepting and having relationships without choosing ‘the one’ until they feel they have the financial means to secure a lifestyle which reflects their achievements. The tragic flip-side is that contraception takes away a woman’s right to say ‘no’ on anything but moral grounds and as the concept of ‘morality’ is such a moveable feast in the secular world, it’s almost a given that sex is expected in a stable, adult relationship and therefore, contraception is presented as the ‘rational and responsible’ choice.
My friends who have married and had children in the their late 30s and early 40s (yes, it can and does happen, even without IVF) have a very different outlook on life than they did in their 20s and early 30s. They suddenly seem to realise who lucky they are to have their children and they become obsessive about providing ‘the best’ and giving them the sort of picture book existence that they ‘sort of’ remember from their own childhood and all the Enid Blyton books they read
If having more than 2 children means having to forgo staying at home, or using a day nursery that is extremely well run, they genuinely see that as a reason for restricting their family size. One lady I know who is intelligent, caring, still mindful of her Catholic upbringing and very committed to her marriage insisted she would abort her second baby if he / she was diagnosed with any chromosomal abnormalities because she wanted ‘only the best’ for her already born toddler.
Of course, there are the lazy, feckless individuals who use contraception as an excuse to sleep around and take no responsibility for their actions, but I believe many people who use it do so because their understanding of their faith is half-baked and eroded by secular values, so that they genuinely believe that they are doing something that is morally justifiable and do so with genuinely good intentions.

Okay, that’s my expanded take on the ‘why’. I have no idea what we do to address it!
I still have every sympathy for married couples for whom, for whatever reason, are unable to use NFP and still have that deep desire to be true to their faith. This is definitely a group that gets swept under the carpet by the Church.