That is perhaps the current convention in action pictures, but has not been the case in the past. In 40s films, for example, the Impact/Love Interest is often the Guardian, or even the Reason archetype.

Perhaps the one thing that IS rather consistent is that the Love Interest (if there is one) is often the Impact Character, regardless of the objective role, archetypal or complex. Still, in Star Wars, Obi-wan is the Impact Character, but Leia is something of the Love Interest.

That is one reason that thinking about Heroes, Villains, and Love Interests is much too indelicate to describe what is really happening in stories. Though certain combinations may come in and out of vogue (such as the anti-heroes of the late sixties and early seventies) thinking in conventional terms is contrary to coming up with unique combinations of one’s own that elevate a story as being not quite like anything else.

One final note: In Aliens the Archetypal role of Guardian is split between the Michael Biehn part and the Paul Burke part, each getting half of the Guardian characteristics and half of the Contagonist characteristics.. Biehn is Help from the Guardian, but Temptation (“Nuke them from orbit” - which will never make Ripley face her fear) from the Contagonist, whereas Burke is Hinder from the Contagonist but Conscience (“You gotta get back on the horse!” - which is just what she really needs to do) from the Guardian.

In short, there are no right or wrong combinations, just commonly used conventions which on the positive side are immediately recognizable by the audience, yet on the negative side are predictable and pedestrian.