I actually thought that was really believable. I distinctly remember when I was a child agreeing with a friend of mine that we would be married one day (and I haven't spoken to her in 14 years!) but we never kissed or anything like that (when you're a ten-year-old boy kissing is the grossest thing in the entire world). The ending of the Delta Episode is like that - they're just kids who think they're in love, but only because they aren't mature enough to understand what love is. At the end of the date, May/Brendan just turns round before entering the house, and smiles - not even a hug! I think the "bless them" expression on their parents' faces as they leave for their date speaks volumes: it signifies that they are just starting out on a long, long journey to adulthood, of which their parents are both proud but simultaneously feeling they have lost something.
Damn, I never thought I'd be writing this kind of stuff about a Pokemon game...