Trivers' core message, in one sentence: the sex that invests more per offspring becomes a limiting resource for the other sex, so relative parental investment, not sex itself, controls how sexual selection operates.
Whichever sex invests less (usually males, because sperm is cheap) competes among themselves for access to the high-investing sex, and the high-investing sex becomes choosy. Where the pattern reverses (phalaropes, pipefish, seahorses), the behaviour reverses too: females compete and males choose. That reversal is his key test, and it is why he defines investment as "cost to the parent's ability to invest in other offspring," not as energy spent.
Three consequences matter for your love section.
First, the sexes' interests conflict even inside a cooperative pair. His closing line is that even when ostensibly cooperating in a joint task, male and female interests are rarely identical. He derives desertion and cuckoldry directly from unequal investment curves: whoever has invested more is tempted to stay, whoever has invested less is tempted to leave, and each sex evolves guards against the other's temptation.
Second, mate choice has two separate criteria depending on the species. Where males contribute only genes, females choose genes. Where males contribute care, choice shifts, in his words, "perhaps primarily," to willingness and ability to be a good parent and to complementarity: can the two parents work together smoothly. That is the exact forecast your section says love performs, and it is in Trivers' Table 1, criterion C.
Third, courtship can be read as a test. His Tinbergen example (a female stickleback withholding sex until the male's freedom to brood was demonstrated) reinterprets courtship as an assay of the partner's future behaviour, not just species and sex recognition.
Persistent conflict inside the bond, and mate choice as forecast of parental cooperation in high-care lineages.
It does not support that love builds a joint predictive procedure.
Trivers stays at the level of evolved strategies, not learned pair-level organization.
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