Aguantar means to endure, tolerate, or put up with something or someone. It's a versatile verb that often implies a struggle or a test of patience.
In this song, Cristian Castro sings, "Vete y busca quien te quiera, quien te aguante a tu manera" (Go and find someone who loves you, who can put up with you your way). He uses aguante to express his exhaustion with his partner's difficult behavior, suggesting that only a very patient person could tolerate her.
This is a breakup song about walking away with your dignity intact. The singer tells a partner who has hurt him, or would hurt him, that letting go is "mejor así" ("better this way") rather than staying in something built on lies.
He opens with a warning: "Si fuera por ti, me harías sufrir" ("If it were up to you, you'd make me suffer"), "casi sin pensarlo podrías mentir" ("almost without thinking you could lie"). Rather than accept that pain, he chooses to leave first: "No juegues conmigo, es mejor tu adiós" ("Don't play with me, your goodbye is better").
The chorus turns the breakup into a clean dismissal: "Vete y busca quien te quiera, quien te aguante a tu manera" ("Go and find someone who loves you, who puts up with you your way"). He's tired, not devastated — "Tan cansado estoy de ti, es mejor así" ("I'm so tired of you, it's better this way") — and repeats that line like a mantra he needs to believe.