I confine my remarks to Plato, who dominates your question
Plato, Aristophanes & the Symposium
Plato does not identify himself or the Platonic Socrates with Aristophanes' view. Aristophanes was a comedic playwright and he is here represented as in humorous mood, engaging in a jeux d'espirit. The story of the original three sexes and of Zeus' bipartition, with each half of a human being yearning and searching for its complement, is not offered or meant to be taken as a serious philosophical view - certainly not as Socrates' or Plato's - which is not to say that it lacks a certain profundity and suggestiveness.
Plato and marriage
Humankind's ultimate perfection, which is perhaps most fully elaborated in the Republic, is a state of eudaimonia or well-being, the true and absolute human good, in which a moralised psyche, "doing well" (eu prattei), practises justice or dikaiosune as the health of the soul. (Republic, IV.444c-445b et passim.)
At no point in the Republic or elsewhere does Plato suggest, so far as I know, that 'celibacy inhibits man's perfection'. On the contrary for the guardian class in the Republic, the phulakes, marriage is replaced by a communal arrangement in which after procreation, involving purely temporary and functional unions, no child knows its parent or parent its child (Republic, V. 460 ff.) Plato sometimes calls these unions 'marriages' [M1] but the term carries in this flattened-out usage no sense of lasting fidelity to and intimacy with another individual person [M2].
Unions of the M1 sort are necessary because procreation is essential to the continuation of the state. But nothing, and certainly not marriage in the sense of lasting fidelity to another individual, must weaken or undermine the guardians' properly single-minded concern with the activity of ruling. If acccompanied by marriage, sexual activity would be apt to deflect the guardians' from vital public to selfishly private and personal preoccupations. (Republic, V passim.)
Marriage as a concession to the elderly
Of course, when women and men pass the age for producing children, we shall declare them free, presumably, to have sex with anyone they like ... [GT: but injunctions against incest qualify this freedom.] ... (Republic, V.461b-c; Plato, The Republic, tr. T. Griffith, Cambridge: CUP, 2000: 159.)
At this stage there is no harm in marriage as lasting fidelity to and intimacy with another individual person [M2]. The elderly guardians, having passed out of public life and no longer responsible for the self-denying rigours of ruling, can harmlessly enjoy what pleasures remain to them.
Here I have concentrated on Plato's prescriptions for marriage - M1 & M2 - within the guardian class. He is more relaxed about marriage among the bulk of the population. But then, the general population are incapable of full human excellence on Plato's view, so what applies to them sets no standards for human excellence and the institutions, such as marriage, appropriate to it.