What does he mean by "this all or nothing"?

Native speaker’s answer
Rebecca
Here, he's using the phrase "all or nothing" as a way to describe and label their relationship. He's using "this" as a determiner for the label. "All or nothing" means that there is no compromise. Everything's either all about the relationship or not at all. There's no in-between. Ex: I either go all or nothing when it comes to working out. = I either exercise excessively, or I don't exercise at all. Ex: It feels like it's all or nothing for the university exams. We have to get into Cambridge.