To be honest, the Doctor is responsible for the situation. The Tardis chose this marital status, right? But the doctor is connected to the Tardis so he had to know what was going to happen. It was really not fair on Rose, to put her in that situation and she is making her sick with worry, thinking she is betraying the doctor when he is the one responsible for this mess.

And yes, in the end, she will have to "kill" this man. So I would say, Rose should let have him some happiness. He deserves it.