Altruism bias (cf. Selfishness bias)
The tendency to moralize and put the fulfillment of other's needs and desires ahead of your own. Even though we wouldn't want others to sacrifice themselves for us (for example, would you want your spouse to stay married to you for your benefit, but not for his or hers?), we embrace a double standard by sacrificing ourselves to others when we are affected by the altruism bias. This bias upholds a lose-win dynamic approach to your relationships with others (where you are loser and "the good guy").
Example: "I really need to be careful about how I spend my money, but I think I must give my friend John another loan, even though he hasn't paid back the last one."
The altruism bias in compounded by many other biases: Attachment bias, Defense bias, It's-about-me bias, Looking-good bias, Resistance bias, Short-term bias, and Victimhood bias. In most cases, the best countermeasures to the Altruism bias is to check if your choice supports a double standard and to consider the transaction and relationship at issue both long-term and short-term.