...wasn't there those behind-the-scenes shots of JB and GDL hugging in a RPS-baiting way outside the "Thames House" building? We didn't know Ianto was on his way to his death at the time *sob*

Plus lack of sexual tension: a lot of that down to Euros Lynn's direction IMO. He's quoted as saying on set "Hug like soldiers, not like lovers" - in TW mag, I think - so they did as directed.