Okay. I give up. I don't get it. I've rewatched the first two and a half episodes now, and I still don't understand where all that clingy!abused!Ianto and asshole!Jack and tragic!unrequited!love is coming from. I didn't see any of that the first time - in fact I had a lot less issues in this respect with CoE than I had with S2 -, but after everything I've read since I thought (was afraid, to be more precise) it'd be pretty much unavoidable. I'm still not seeing it.
( And the irony is... )So I've really been wondering if I do have issues that I wasn't aware of on top of all the issues that I
am aware of, or... actually I don't know what the alternative would be.
What I'm seeing is two people working out the terms of a very complicated relationship.
Take
Day Three, the 'We better make the most of it' scene.
Jack clearly isn't happy to discuss his dying and coming back again, most likely because very probably every single discussion he's ever had about that with people he loved has been painful and doomed from the start, and even addressing the subject is a reminder of every person he lost over it, one way or the other. So when Ianto wants to discuss this now, after Jack's most recent and most dramatic death that took the Hub and the remainder of Torchwood with it, I think Jack more or less excepts Ianto to be finally unable to deal with it. He can't change it, he can't (and won't) lie about it, there's no point in sugar-coating the truth, so it may sound a bit brusque, but I think that's also because he's essentially preparing himself for Ianto to break off whatever relationship they've had so far.
Especially when Ianto brings up the point about aging that bothered Alice so much she wanted Jack out of her life, just like her mother. Most recently
a bare couple of days before. And Alice's other point, that Jack was dangerous to the people around him... well, the explosion already proved that, just in case Ianto (or Jack) needed another reminder.
And then it's a bit like the end of
They Keep Killing Suzie all over again, with Ianto actually surprising Jack, pretty much declaring this a relationship -
'We better make the most of it then'. Because the thing is, Jack couldn't ask then, not after the whole Lisa disaster, and I don't think he believes he really has the right to offer a relationship that is fraught with so many issues and bound to be both painful and dangerous to the person he loved, so once again it has to be Ianto.
But looking at Jack's smile, I think it's pretty clear he's mostly happy about it. It's a bit bittersweet, not the usual brilliant movie star smile, because he can't ignore the knowledge that at one point this is going to hurt like hell, certainly him, more likely both of them, but it's genuine.

And considering all the 'love' vs. 'just sex' debates during S2, it's maybe worth pointing out that it's made very clear that Jack's reaction has nothing to do with kinky stopwatch sex this time ('the world is ending').
And at this point at the very latest? It's no longer unrequited.