Being Selfish Should Be a Art Form You Know

They always say that being selfish is a bad thing. Society manages to make you feel guilty for being selfish. It is considered socially unacceptable to be such a thing.

If a mother is at the end of her rope with a toddler or new born and she wants "me" time or she wants to go off by herself, she is considered selfish for wishing to do so. I believe in that situation it is the complete opposite. She is doing the right thing in the fact that she is re grouping herself. She is calming herself down so she can be the best mother she can be. Yet society deems her to be a selfish self interested mother.

I wife decides she wants to go out and do her thing instead of catering to a husband and his needs and society deems this to be selfish??? ....

All of this makes no sense to me. I will admit though sub consciously I have bowed to societies ideas of what is social unacceptable in the selfishness department.
I am the type of person that will continually put the needs of others before myself. I do it because I am a nice person. I have this unwavering belief that karma will eventually bite you back in the ass really hard. I believe in the phrase no good deed goes unturned. But recent events have made me realize that maybe I should be selfish ....
Someone I "like" basically has to make a decision between me and something else ( here comes that whole anonymous thing mentioned in the below post again lol) so I cannot mention the something else out of respect but be safe in the knowledge that the something else is a very big thing people.
I have done the Louisa response of " you have to look after yourself and do the right thing, and I support you"
Wellllll for the first time in a very very long time I completely regretted what I was saying. Inside I was screaming PICK ME PICK ME !! ( like I am a nose or something lol ) I just recoiled in fear inside at the thought that I would not be first to be picked. I panicked that I was losing something that potentially could be very very good and amazing.
I hate this feeling. Its like the old tug of war between right and wrong. Do I unselfishly fully offer my support. Do I attempt not sway the decision in my way do I be the "nice" person I have always been ....nice does not necessarily always work though.
Or do I be something so very foreign and against my nature and grain. Do I become a selfish person and pray I am picked or sway the decision somehow that I am picked? Being selfish is a foreign concept to me. Its something a lot of people have no issue being but for me it is not in my nature it is not something I can do naturally or with ease. But you know maybe this is the time that I do throw myself out of my "nice" comfort zone and take a chance.
Hmmm right my ramble is complete I am no closer to being clear minded or having a clear thought pattern if anything I have now made it worse dammit !! lol