You could either "go for a walk" to go directly to path D, or you "go to the bathroom", then go the "marriage path" till "marriage sucks" and choose the right option there to go to path D. The last path D scene is different if you've chosen this path, all other scenes are the same...
I personally always go the marriage path first because I like the alternative scene... ^^
I made a flowchart for Sam some time ago, if it's not clear enough:
https://attachments.f95zone.to/2021/03/1090221_flow_sam.png
Which one "marriage sucks" or "cheater got pregnant"?
"Marriage sucks" is the only way to progress her story further if you've chosen to go that path. "Cheater got pregnant" is easily avoidable by either using a condom or cumming outside during "marriage sucks"...