Perhaps that's where DA2's romances fell short with me personally because straight off the bat we could flirt with them, we couldn't really build up to it or get to know them as acquaintances and then friends like you would in real life/could in DA:O. At times it felt inappropriate to have the option to flirt with them at all, like right after Karl died with Anders' first quest, lol!
Well, you have the option to take that flirt but you don't have to. You don't have to flirt with anyone in Act 1. So if you want, you could wait to get to know the companion before beginning a flirtation in Act 2.
I'll agree that the Anders flirts often seemed inappropriate though lol And his romance does indeed feel rushed. Partially because he's so ready and willing lol You flirt with him in Act 1, and he's like YES! Let's do this NOW! I mean, whoa boy! We just met! Fenris' romance is better (for me) because he keeps holding his hands up and saying, um, not just yet, okay? So it's more organic.
I think Isabela's romance plays out really well, too, since after you sleep together, she acts like it meant nothing, then she disappears in Act 2, and when she comes back it's such a sweet surprise! Then feelings happen in Act 3 lol
I think it was Anders lack of Act 3 romance stuff that made his romance so blah for me. I mean it basically ends in Act 2.