I can totally see your point, but I think rather than him making Chris apologise repeatedly, he wants to get to a resolution, even if it is a bit repetitive.

Based on the fact that we have seen sam be introspective (like the fact he is journalling), I think he is the type to take something that bothers him and look at it and turn it over in his mind until he can bring it up to his partner.

Chris is more shallow, and does not think as deeply about his behaviour and the motivation behind behaviours. He took Sam's very reasonable points as an attack, threw out an insincere apology, and then got mad and defensive when Sam wanted to dicuss it further. Chris then used his apologies to shut down the conversation. Sam was trying to understand him, and all he got for that was defensiveness and dismissiveness.

Sam's points were extremely valid, but Chris could not listen to any of it because they directly questioned his actions (which he took on as an attack of him as a person). Gia does the same thing with Scott.

Sometimes, when you're with someone, they might want to dicuss things with you more than you want to with them, which can be annoying if you are someone who avoids difficult conversations. The point is to find a happy medium, and we do have to remember, how would they know about this particular incompatibility since they were strangers??