Peleus was mortal, though (albeit grandson of Zeus). He needed help in catching the sea-nymph, who wasn't going to surrender quietly.
"He woke her with a kiss.
First she was astonished, then furious.
He applied all his cunning to seduce her.
He exhausted his resources. None of it worked.
His every soft word hardened her colder.
If they had been two cats, he was thinking,
She would have been flattened to the wall,
Her mask fixed in a snarl, spitting at him.
He took his cue from that. Where argument
Fails, violence follows. His strength
Could have trussed her up like a chicken
If she had stayed the woman he woke with a kiss.
But before he knew
He was grappling with an enormous sea-bird,
Its body powerful as a seal, and its beak
Spiking his skull like a claw hammer.
A bird that was suddenly a wren
Escaping towards the tangle of myrtles,
Bolting past his cheek like a shuttlecock
That he caught with a snatch of pure luck,
And found himself
Gripping a tigress by the shag of her throat
As her paw hit him with the impact
Of a fifty-kilo lump of shaggy bronze
Dropped from a battlement.
He rolled from the cave and landed flat on his back
In cushioning shallow water."
At first defeated.
The sea-god Proteus gave him an answer, telling him to bind her with leather thongs, and not to let go, NO MATTER WHAT.
"'...bind her, bind her tight with thongs,
Before she wakes. Then hang on to her body
No matter what it becomes, no matter what monster.
Do not let her scare you--
However she transforms herself, it is her,
Dodging from shape to shape, through a hundred shapes.
Till her counterfeit selves are all used up,
And she reappears as Thetis.'"
Thus did Peleus, and thus he won his sea-nymph bride.
And I was thinking about being like Thetis myself: wanting someone to hold onto me, no matter what. Having that commitment, no matter what. Loving me, no matter what. Knowing that I am in there, and worth it, no matter what. I think more than a few adoptees feel like Thetis, and want (not necessarily to be bound), but to be held and loved, not matter what face we show, what mask.
Perhaps it's all about reframing the question. It's not that we aren't good enough for people to hold tightly: it's that we're like sea-nymphs, and more valuable than we even know.