Besides, unless you think of time as a nebulous concept, aren't all relationships a linear, step-by-step process?
I'll use what someone else said as a counter argument.
BG2 is a great example of why you shouldn't use that linearity (well, at least not on everyone)
When you romance Jaheira, if you follow the game events and have sex with her before she's had the time needed to go through her issues, she will start crying remembering her dead husband and will either break the relationship removing every flag or completely leave the party.
And to me, this is great. This is a moment that makes you go:
"Well fuck... why did I just think with my dick only and not my brain?" and
"She's been complaining about her dead husband for 30 real life hours and my best idea was to fuck her... I'm a retard."