Just from what he's said, TJ realizes she wasn't wrong: it is complicated. She's not sure where to start unpacking his entire statement: the ex running off, the time machine, someone exciting? But it seems like it all bothers Ianto a lot and she doesn't want to dwell on things that might make him feel worse, at least where his ex is concerned, so she hums encouragingly, or so she hopes, and tackles the last bit first.

"What happened that makes you think you ruined everything? You mean with Colonel Sheppard?"