It’s an interesting one @HildegardeCrowe and not quite as clear cut as being a Tamagochi (though that did amuse me too).
I’m a few months into a relationship with a man a bit younger than yours (we are both mid-late 40s) who overall is just not as into messaging as I am. If I was ever to audit our WhatsApp I’m sure I account for 75% of the content and “initiate” way more chats than he does.
It concerned me a little to begin with - as in, is he not thinking about me, into me etc. BUT - he is just not a phone person. As in when we are together he doesn’t lift his phone and scroll by default the way so many people do (myself included). And I really like that about him.
I’ve not heard from him today - and that’s ok. We spent 3 days away together at the weekend and then he dropped everything to come with me to something at short notice last night when someone else dropped out. He SHOWS me he cares about me, rather than sending formulaic good morning messages.
So whilst people are saying you can’t change your preferences or whatever, I think you can. I have. I have reframed the importance of messaging as something that can be easily and emptily done, esp by a phone addict. I look at the other things he does / says when we are together. Don’t let a good man get away because of this 
I certainly wouldn’t be asking for extra messaging - but you can positively reinforce I guess when he does message. But in a non-overwhelming way. I also think how unattractive to have a guy so lacking in confidence / busyness that they were texting me every minute of the day.