The importance of age difference kinda works on a sliding scale; the older the youngest party is, the less it matters. So for example if the younger party is 19, any age difference greater than 7 years or so is bound to raise some eyebrows; over 15 or 20 years and it'll definitely raise some red flags, or possibly alarm bells.
Though if the younger party were older, say late 20's to early 30's most people wouldn't bat an eyelid at a difference of 10-15 years. If they're both past 40, nobody gives a crap either way. It's all about balanced power dynamics.
While in theory; sure what consenting adults get up to is their own business. However I think it's a given that in most cultures there's a degree of impropriety involved when the age difference gets to be cross-generational. Of course there's always exceptions, though those typically involve political/economic marriages or the kinds of behaviours restricted to certain protected classes in society (typically of the wealthy persuasion), mostly for all the reasons that lets people of that ilk get away with just about anything. Or when one of said parties (typically the female) doesn't get a choice in the matter; basically social and/or religious slavery as was the case with the literal sale of brides from convents...only for the discerning gentlemen of means, of course.
Fun side note: the etymology of the word "privilege" basically boils down to the Latin words for "private law". As in the law the ruling class can impose but not be bound by. Hence all through history crusty old aristocrats/emperors/chieftains/oligarch/whatever are carrying on teenagers, and everyone around them feigning sudden blindness and short term memory loss.
...Aaaaanyway, none of this applies to Daisy and Sousa. One is in her early 30's by this point, the other is in his mid to late 30's. Nothing potentially suspect there at all. Well, unless you go chronologically then Sousa is a little over 100 (and dead) in Daisy's end of the timeline and Daisy was negative 33 or so when they first met in '55. Such is the subjectivity of time travel. Though if it helps at all, Daisy's mum is almost certainly older than Sousa, so that probably balances things out.
