If we're talking about a non-culture war answer. It's a combination of the following factors, some of which are self-perpetuating loops:

• Decline in social skills due to internet + Decline in skills due to decline of third spaces
• Decline of third spaces stemming from economic slowdown compared to the 00s and 10s + hence the few remaining third spaces are more expensive, due to them running at a premium. This means both fewer places to practice social skills, hence, inferring a decrease in positive social outcomes that lead to 'dating', as well as fewer actual places to meet people of the opposite sex, hence, a reduced dating pool.
• Atomisation -> It's very easy to fall into patterns where we're only exposed to people who share our interests. However, due to a combination of social and biological factors, obviously some hobbies are going to be male dominated, and some hobbies are going to be female dominated.
• E.g. this is why for example, a hypothetical woman who goes out to spin class every week, yoga, cafes, may constantly be "out", but the number of men who the hypothetical woman might meet could be in the single digits, if that's what the demographics of her personal social landscape dictates. You can do the inverse and replace 'woman' with 'man', and you get the same results.
• In contrast, looking at the couples that do still meet outside OLD, you can see a clear pattern of third spaces such as church, university/highschool, as the latter two are often some of the last places where most people will be around lots of single people their age.
• Online dating gaining a plurality in the dating market (more than 70% of couples met online) combined with OLD regressing in actual effectiveness -> It's just not a pleasant experience for anyone involved, because the economic model OLD apps use to maximise profit doesn't also maximise coupling
• Social attitudes are still very much antiquated. This is the only vaguely "culture war" point, and it's not due to "ze evil MRAs/feminists". But consider this:
• Men are generally expected to make the first move across most cultures where this is commonly an issue
• Dating expectations are still rooted in attitudes that grew from the 90s/00s era of prosperity. E.g. paying for dinner first dates are a common ask seen in OLD. (Not a moral judgement, this is just reality)
• Men are increasingly falling behind on job metrics, or rather, if we're being positive, women are outcompeting men.
• However you dress this, this means in the dating world, the first move, due to the above factors, is costly for men as initiator, in a time when men have less capacity for costly adventures. I am also going to mention navigating shifting acceptable social behaviours is an increasingly difficult task, given aforementioned decrease in how socialised people are.

Me personally, even as someone earning decent money in a large city, economic conditions have made me wary and fiscally conservative (I try to put about 2/3s of my post rent salary in stocks/tax shielded savings accounts/misc saving accounts). My work and hobbies are very male dominated, and that's fine. I've made my peace with that. I don't expect a partner to fall into my lap. So I see dating as something I have to actively allocate time and money into, so I pick and choose when I engage with it, and often, that's just not a lot of the year at this stage in life.