Because he feels the same, he can't be truly angry at her. The guilt is just a facade, an excuse that will get overcomed over time.
The entire premise of day 6 is to show they can't be without each other. For that I made the deliberate choice to have them mostly converse through the phone, eavesdrop, have internal monologues... They don't interact much directly until the night.
About the wine, it helped because he wouldn't have had the balls yet to talk about those things with her without some alcohol during that night. And then the next day the full reality of the situation comes crashing down and he breaks again.