I don't really remember Fragile Balance and Grace, so I can't really comment on that, but Sam and Jack seem to be friends, not just have that working relationship. They're somewhat formal when it comes to titles, but other than that they don't seem to really respect the boundaries they're supposed to have. Even if you don't ship them (which I don't particularly), you have to admit that they're closer than they should be by military rules.

Lee and Laura respect each other, definitely, and they have a lot in common, but they're not friends, and they're not equals. Maybe over time they could build more of an even relationship, but right now they still seem to be keeping something of a professional distance.