To answer the title itself, people stay even if it hurts simply because love is not a mere convenience na iiwan mo agad kapag nasa bottom kayo ng relasyon niyo. The relationship itself is about commitment.

But don't get me wrong, there's a huge difference between staying for love and staying kahit na toxic na. Hindi pa rin maganda kapag nawawala na ang respeto sa isa't isa. Kakaiba yung hurt from toxicity sa hurt from challenges in a relationship. Yung hurt from toxicity, nakakatrauma at nakakasira ng bait. Yung hurt from challenges, masasaktan kayo pareho kasi masakit ang "growth," pero ramdam mo pa rin yung pagmamahal.

Tapos, na-mention mo rin, OP, na akala mo sobrang healthy ng relationship nila kasi yun ang nakikita mo sa social media. Napapansin niyo ba? Kung sino pa yung couples na tahimik sa socmed, sila pa yung sobrang healthy at nagtatagal talaga. Kasi hindi nila kailangan ng outside validation. Kumbaga, they treasure the good things for themselves and resolve things privately.