To contribute some things I think people are missing from this chapter. Pay attention to the panels since the wife's hair also looks like Kiku-san's, the outfit is the giveaway.
The dad was a smoker, that's why he had the lighter, why "responsibility" is paired with the a man smoking. It explains how and when he actually MET Kiku-san, at the hospital for lung cancer treatments he was hiding from his family as BadmanBlues pointed out. It also explains why his blood is in a hospital refrigerator and the image of his blood being drawn, most likely for lab tests for his cancer. His "despair" while being confronted by a doctor is him being told it's terminal, he won't recover.
THEN we see "repentance", but he'd done nothing wrong in these memories yet right? Unless he was already with Kiku and cheating with her, but he also became a vampire in the end, which tells us she'd bitten him already by then and he'd fallen in love with her as well. You can see at "honesty" that her eyes go wide, then she looks away, dejected. She was the one who HE rejected, not the other way around. The "...? pain" here is his confused emotions, since we know he actually loved Kiku since he became a vampire but broke it off with her anyway. She was also meeting with him on the rooftop, which I imagine she wouldn't be willing to do with a patient she had no interest in and would reject herself.
"Determination" and "atonement" showing the apartment building they lived in, he was determined to atone to his family, "gratitude" with a picture of his wife, thankfulness that she was really willing to forgive him. Then "bonds" and the picture of the lighter his daughter had given him that he loved so much it became his weakness. Then "let's start over". He was a vampire, he would almost certainly live despite his cancer. He loved his daughter more than he loved Kiku, so he left her and wanted to live as a vampire, hiding it, and love his wife and daughter. It also explains a lot of his behavior right before he killed her and died himself.
The alternative path is only slightly different in that he actually thought he was going to die from the cancer, cheated with Kiku because he thought he was dying, fell in love, got bitten, and then got the news he was actually going to LIVE. The despair is from realizing he's cheating on his wife for no good reason, and that what he did was selfish and undeserved. He then breaks it off with her, same as the other option. Some very minor details that effect only a few things in the order of events and motives.
One thing for certain is he broke up with Kiku instead of the other way around as he said he had in chapter 81("I broke up with them, I honestly remembered what was important to me"), and that he was truly planning on being there for his family after repenting and feeling guilt over everything he'd done. He also kept smoking, so it's most likely he wasn't worried about the cancer anymore, plus he said he'd "never felt like drinking blood before (then)" so he was also banking on himself being a vampire.
EDIT: It also explains why Kiku-san remembered him and as the detective said "left an impression" on her, I imagine it wasn't often she was the one getting dumped. It also explains why she knew her name in chapter 156, he told her about his wife and daughter and that she was why he was breaking up with her.
