It's not uncommon for a parent or spouse to be willing to sacrifice their own life to save someone they love.
Having said that if you are talking about people who are willing to be a "doormat" for their mate by taking verbal/physical abuse, accepting infidelity as a way of life, or giving everything they have while getting nothing or expecting nothing in return, and would contemplate suicide if their mate ever left them....etc Yes! There are people like that!
Anyone without "deal breakers" generally has low self-esteem or lacks self-love. One man's opinion! :-)