The first couple is mildly inappropriate (uke being 19 and in the spectrum and seme being 25 and a bit of creep) but mostly harmless or even fluffy. The second on the other hand has an even worse age gap and actually met when one was 19 and the other was 12. Their story is mostly about the young seme staking the uke and ultimately coercing him into a relationship mostly through guilt-tripping. It's honestly creepy and sad. To make it even worse the author seems much more interested in the second couple. There are only 10 chapters about the first couple and 29 about the second.
Heart no Kakurega