my personal preferred flavor of aroace grace is:

a) he has no idea that that's what he's got going on. he knows of the terms but he's got some subconscious queerphobia going on and feels like those words are only for purple haired teenagers. and he's in favor of purple haired teenagers, but that's still for Other People, it would never in a million years apply to him.

b) his "leaf in the stream of creation who just kinda does what other people ask him to" attitude extends to his interpersonal relationships and he very much has always fallen victim to the mindset that he needs a "good reason" to refuse someone romantically or sexually. mostly this means he's had a lot of pretty miserable experiences that were uncomfortable and felt bad but where the other person didn't actually do anything wrong, everything was completely above-board and as it "should" be and he still haaated it. his takeaway is that relationships and intimacy are inherently unpleasant for reasons he can't describe and in a way that he can't alter, so he'll just silo himself away from getting close with people to avoid the risk.

and c) well. that's not quite true, strictly speaking. as I said, he does know of the terms, he could think one step further and fully connect the dots. in the back of his mind he thinks about how there's maybe a version of his life out there where he's Better at everything and is able to voice his feelings and get those intimate relationships without the parts he can't handle. maybe, if he tried, he could find someone who would hear all his little buried thoughts and inadequacies and not immediately kick him to the curb. but that sounds terrifying, so he doesn't do it.