x1=m1=xa1 finishes consuming x2=xa2 by standard x3=m3; x1 has had their/its fill.
xakmu'o focuses more on the consumer. selxakmu'o means exhausted. Note on lujvo construction: as a lujvo, xakmu'o does not elide se from the seltau (see CLL 12.9 guidelines) and, rather than applying the general bridi relationship to m1 as a general principle, links xa1 to m1; if this particular nuance is desired, then besides mulxaksu, constructions like nunxakmu'o and selselxakmu'o for the former and latter (or simply using an explicit bridi) may perhaps be used.