comment #10329 Walking home with your boyfriend under the same umbrella is a classic form for several character types; especially Haruhi's tsundere.
She (or both of them) won't admit she just wants to be with him for whatever reason, but she can pretend there is no choice but to walk home under the same umbrella. And of course, sharing the umbrella has the advantage of having to walk closely together.
Another mutation of this form would be the umbrella party encountering the girl, with her clothes sopping wet from the sudden downpour, and walking back to her house so she can change (and probably have hot wild sex.) Easy attachment point for a bath scene too...
I like it. You can categorize scenes like that as much as you want, however it simply works. Probably even because it is common and romantic - if you think it isn't, then you've obviously not experienced it for yourself.