Disclaimer: I don't own the show. If I did Gwen wouldn't be the one to be left alive.
A bit of Gwen bashing in here.
Gwen Cooper was sure that Jack was the man of her life and she wasn't going to miss her chance of happiness. She was absolutely convinced that they we're born for each other, but there was this one little matter of her beautiful captain being convince that he was in love with Ianto Jones. She had never believed that Ianto will be the one to make jack Harkness stay with only one person, Gwen had always expected for Jack to cheat and for Ianto to throw him out. Than she would seize her opportunity, she only needed to be patient. But yesterday Jack had confined in her that he was going to propose to Ianto and this made Gwen want to scream and rage. Still she kept cool and smiled and wished him luck, all the while planning on how to sabotage the wedding if not the engagement.
She was going to throw Rhys out and tell him that she had changed too much now and she wasn't the girl that wanted to marry him anymore. She could even try to tell him about her affair with Owen if Rhys persisted on saving there relationship. She was going to get Jack to sleep with her and make anything possible to conceive a child with him, so he would not abandon her to be a single mom and will leave Ianto. Her mind made up, Gwen went to the archives in search of artefact that will allow her to get pregnant even just from the one night. They she will have to find a way to drug or persuade Jack to sleep with her. Ideally Ianto will catch them in the process and have this sorted out with minimum effort. She didn't really have anything personal against Ianto, he wasn't much of a match for her. He was just a shy and boring office boy, but it seams that he had managed to catch the eyes of the captain. Who would really have him she didn't now, and that was why she was convinced that this can't be serious and last, not with a man like Jack Harkness.
Jack was fiddling with the collar of his shirt and checked his hair for umptied time in the mirror to make sure that everything was perfect. He was going to propose marriage to his boyfriend Ianto Jones and wasn't sure how it will be received. What if Ianto said no? Gwen had reassured him last night that Ianto wouldn't because he loved him but he started having his doubts again. They had never admitted to each other that their loved the other. They never even talked about a relationship, but after Rhys and Gwens wedding was coming closer, Jack started to think that it was time he made it official with Ianto and stopped the Welshman's doubts about his status in Jack's heart.
Just when he was finally picking up his courage and opened the hatch door of his manhole to go and find Ianto , Gwen entered his office out of breath.
"Jack you need to come and see an artefact it gave a pulse that almost blinded me. I know you have to talk to Ianto, but I don't know how important this is. Just come for a minute. "