I already talked about most of this stuff but I have a few things to add so you're getting it again.

To me, their relationship started very differently from pretty much every relationship Jabber has. Since it started as just casual chilling together, I think Jabber views his relationship with Momoa as its own special thing (which it is!). He uses that to justify why he's so content receiving soft affection and touch from her when when he wouldn't like it anywhere or from anyone else. (It helps that Momoa also isn't super touchy and she usually lets Jabber initiate it anyway. They use each other as resting spots a lot lol). Also, since Jabber views Momoa as strong despite her not being a fighter, that leaves her in a weird position in Jabber's mind. He loves hurting people and he loves a good fight, and Momoa's not a weakling so he doesn't feel a need to hurt her outside of a fight, but she doesn't fight, so what is he supposed to do?

Momoa acknowledges Jabber's sadomasochism and doesn't give a shit about it, but she also knows that it's a fundamental pillar of what makes Jabber Jabber. Since she doesn't fight, I think she will aggravate his injuries for him sometimes, but she almost never hurts him herself. That's the extent of how Momoa indulges his masochism, which Jabber is okay with because he views Momoa totally differently than the people he fights.

As for his sadism, this is where they struggle more. Momoa isn't interested at all in being Jabber's test subject (even though it would make him happy to test toxins on her) and Jabber respects that, but it also leads to a corner of their otherwise well-rounded relationship being unfulfilling for him. So he settles for pranking her which can occasionally go too far, but Momoa puts up with most of them because she acknowledges this is another way Jabber is trying to connect with her. That doesn't mean she's a pushover though.

Momoa acknowledges the ever looming danger that comes from being with Jabber. She knows he could seriously hurt her at any time and she actually enjoys the risk that comes with that. But their relationship isn't an SM one, so she knows it very likely won't come down to that. Similarly, Jabber knows the threat that comes with Momoa knowing his mentality and trauma very well. She could seriously hurt him too, and he accepts that risk. (Though he enjoys it a bit less than Momoa enjoys the thrill of living on the edge of danger. It still is something that makes her alluring to him, though.)