When your partner isn't interested in practice
The Buddha's picture of a good partnership — Nakula's parents, matched in faith, conduct, giving and understanding — is an ideal, and the suttas do not say a marriage without it is failing. Many lay disciples practised beside partners who did not. The canon calls good friendship the whole of the path, and a friend in the practice need not be the person you live with. Its training in love begins with the specific person in front of you before it widens. What the suttas cannot tell you is whether the distance you feel is about practice or about something practice has made visible; that is worth saying to each other in words that are true and timely.
What the suttas say
Householders, if wife and husband want to see each other in both this life and the next, they should be equals in faith, ethics, generosity, and wisdom.
Nakula's parents — the Buddha's picture of a good partnership.
Where this stops: A picture of a partnership both people want; not a standard to measure a partner who broke faith against, and not a reason to stay.
AN 4.55:3.1 · Equality (1st)
Ākaṅkheyyuñce, gahapatayo, ubho jānipatayo diṭṭhe ceva dhamme aññamaññaṁ passituṁ abhisamparāyañca aññamaññaṁ passituṁ ubhova assu samasaddhā samasīlā samacāgā samapaññā, te diṭṭhe ceva dhamme aññamaññaṁ passanti abhisamparāyañca aññamaññaṁ passantīti.
Even as a mother would protect with her life her child, her only child, so too for all creatures unfold a boundless heart. With love for the whole world, unfold a boundless heart: above, below, all round, unconstricted, without enmity or foe. When standing, walking, sitting, or lying down while yet unweary, keep this ever in mind; for this, they say, is a divine meditation in this life.
The Metta Sutta's central image, in the canon's own words.
Where this stops: The verses are an ideal of the practitioner; the opening lines describing a skilled and honest person are a description, not a prerequisite for beginning. Never use it to quiet anger that has something to say, and never present it as a recitation that protects anyone. The mother guarding her only child is not for someone after a pregnancy loss.
Kp 9:7.1–9.4 · The Discourse on Love
Mātā yathā niyaṁ puttam Āyusā ekaputtamanurakkhe; Evampi sabbabhūtesu, Mānasaṁ bhāvaye aparimāṇaṁ. Mettañca sabbalokasmi, Mānasaṁ bhāvaye aparimāṇaṁ; Uddhaṁ adho ca tiriyañca, Asambādhaṁ averamasapattaṁ. Tiṭṭhaṁ caraṁ nisinno va, Sayāno yāvatāssa vitamiddho; Etaṁ satiṁ adhiṭṭheyya, Brahmametaṁ vihāramidhamāhu.
“Sir, good friends, companions, and associates are half the spiritual life.” Not so, Ānanda! Not so, Ānanda! Good friends, companions, and associates are the whole of the spiritual life. A mendicant with good friends, companions, and associates can expect to develop and cultivate the noble eightfold path.
Ānanda says half; the Buddha says all of it.
Where this stops: Never used to make someone without such friends feel that their practice is lacking.
SN 45.2:1.4–2.3 · Half the Spiritual Life
“upaḍḍhamidaṁ, bhante, brahmacariyaṁ, yadidaṁ—kalyāṇamittatā kalyāṇasahāyatā kalyāṇasampavaṅkatā”ti. Mā hevaṁ, ānanda, mā hevaṁ, ānanda. Sakalamevidaṁ, ānanda, brahmacariyaṁ, yadidaṁ—kalyāṇamittatā kalyāṇasahāyatā kalyāṇasampavaṅkatā. Kalyāṇamittassetaṁ, ānanda, bhikkhuno pāṭikaṅkhaṁ kalyāṇasahāyassa kalyāṇasampavaṅkassa—ariyaṁ aṭṭhaṅgikaṁ maggaṁ bhāvessati, ariyaṁ aṭṭhaṅgikaṁ maggaṁ bahulīkarissati.
These six directions should be recognized: parents as the east, tutors as the south, partner and children as the west, friends and colleagues as the north, bondservants and workers as beneath, and ascetics and brahmins as above.
The canon's own map of a householder's relationships, the six directions, from parents in the east to ascetics and brahmins above.
Where this stops: Only the list of the six directions; how each one is looked after, parents included, follows it from DN 31:28.
DN 31:27.2–27.3 · Advice to Sigālaka
Cha imā, gahapatiputta, disā veditabbā. Puratthimā disā mātāpitaro veditabbā, dakkhiṇā disā ācariyā veditabbā, pacchimā disā puttadārā veditabbā, uttarā disā mittāmaccā veditabbā, heṭṭhimā disā dāsakammakarā veditabbā, uparimā disā samaṇabrāhmaṇā veditabbā.
We will meditate spreading a heart of love to that individual. And with them as a basis, we will meditate spreading a heart full of love to everyone in the world—abundant, expansive, limitless, free of enmity and ill will.’
Mettā starts with the specific person who spoke harshly, then widens; the order matters.
Where this stops: A training for one's own mind under hard speech. It is never a reason to stay where someone keeps speaking to you with contempt or threats, and never a ruling on whether to leave.
MN 21:11.14 · The Simile of the Saw
Tañca puggalaṁ mettāsahagatena cetasā pharitvā viharissāma, tadārammaṇañca sabbāvantaṁ lokaṁ mettāsahagatena cittena vipulena mahaggatena appamāṇena averena abyābajjhena pharitvā viharissāmā’ti.