I think I would have trouble taking seriously an elder vampire who shacks up with some wet behind the ears neonate.
I'm fine with vampires throwing around a bit of sensuality, but I'd rather that sensuality be a weapon and when some powerful elder starts flirting, that should set off warning bells, not wedding bells.
Yes and no, personally? It should definitely be a weapon - hell, even in the original Bloodlines both Jeanette and VV were obviously manipulating you. But just because it's being used as a weapon doesn't mean that other thing aren't involved (or might unintentionally creep in, or even take over), and that ambiguity is what can make this kind of thing really work (together with your own decision how much you character is flirting/playing along for the same reasons). Can make, because it's rather hard to pull off well, but I'm reasonably confident this writer team has the chops, so to speak.
As for elders... well, first off we have to see how many, if any, are around. Someone embraced at Seattle's founding still wouldn't be an elder.
And I can imagine scenarios where such a pairing up could happen - you're just a neonate, sure, but I'd be very surprised if you stayed unimportant for long (I mean, there are multiple endings. You need to make a difference), so manipulating the player character that way could be worthwhile? And if the elders humanity is high enough, it might become... somewhat less dispassionate than they were intending? So warning bells are definitely appropriate, but it might not end badly... maybe?
Or the elder could be Toreador and just obsess about you, but you don't want that.
I to like and even prefer games with romance options in them.
I hope that we can turn someone into a ghoul like we did with heather in Bloodlines 1 and then they end up staying with you
When they were asked about ghouls in an interview they stated they couldn't take about it yet, so fingers crossed there will be something like this.
Although personally that wouldn't be a romance I'd pursue, because the blood forces them to love you.