Selfishness is unnecessarily maligned.
I believe that if we genuinely know, believe in and stand up for what we want as individuals, there would be fewer problems in our relationships.

We are taught that being selfish is not desirable because it automatically means we do not look out for others. I have learned that the few of us who do not look out for others or even actively harm others, do so because they grew up being treated the same way. Therefore, they will "snatch" whatever they can, just to feel they are deserving.

Most of us can rest assured that a balance is possible between looking out for ourselves and others and there does not need to be a tug-of-war between the two. Please try being "selfish" in relationships and you will probably notice a shift over the long term. That is, state what you would like and try to act on it as much as possible.

As long as your intention is not to harm others, the guilt of feeling "selfish" will gradually dissipate. There is freedom in being yourself while loving others. Dissolving yourself in what others want you to be, is more harmful than being "selfish". 

If you are in a long-term relationship, please ask yourself: "Why am I in this relationship?". If the answer is anything other than, "because I want to be with my partner/spouse", it might be time to make changes.

If your answer sounds like any of these - "because of my kids", "because he/she needs me", "because my parents arranged this", "because I am afraid to be alone" etc.- it is time to make changes.

By 'changes', I do not mean ending the relationship, though that option might be necessary for some of us. I mean working on yourself to see if you can change your answer to- "because I want to be with ...... (name of your partner)"

How do you work on yourself? I believe one needs to introspect, self-reflect, understand the reasons behind one's motivation/ fears etc. One way is to find a therapist who you can trust and who would help you through this process. Ideally, both you and your partner would engage in this work, thus benefiting your relationship. If your partner is not ready, I believe that individual work would still be useful to both you and your relationship.

As I grow older, I realize that there IS a purpose for every challenge I face. That is, if I choose to examine it. That purpose, I have determined, is internal GROWTH.

Please feel free to view life's challenges as presented below:
I Recognize that a challenge is not necessarily thrown my way to hurt me
I Recognize that a challenge is a message for me to try a different approach from what I have done previously
I Recognize that a challenge is meant for me to eliminate old fears and see how strong I really am
I Recognize that a challenge, if used well, brings forth a whole new world of opportunities

Finally, internal growth need not stop, unless we choose to stunt ourselves. Therefore:
I Recognize that I keep facing challenges because I have demonstrated the will and capacity to GROW.