Otherwise known as common sense and things anyone that has ever been in a relationship has probably understood if they're not a brain damaged fucklord. I listened for 10 minutes off and on and maybe I'm just way overestimating the emotional competency of the average vtuber viewer and/or have no idea who this stream is supposed to be for, but if you really need to be told shit like make sure you can tolerate living together, ensure you have trust in each other, plan for various common health concerns with having/raising children, maybe just get castrated so you don't infect the gene pool.