Yes you can, happiness is either there or it isn't. You are either happy with the person you are with or you are not. When you become happy with someone you no longer feel a need to seek others because you are happy with what you have.

The issue with constantly seeking something better and better and hitting a ceiling where no one is ever good enough I believe comes from emotional attachments. People make the mistake of comparing new (potential partner) people to those best they have had in the past. The problem with this is that those best they've had in the past are (usually) those that they have had the deepest emotional connections with. Connections that take months and even years of building, where we know our partners inside out and they also.

No new person you ever meet can hope to live up to such a comparison once you've hit a certain point and thus you hit a ceiling. Couple this with the emotional defensiveness inherent in the community - not investing oneself - and you can see why people get this problem.

The solution is in realising that in order for you to ever find someone that lives up to previous standards one has to actually become emotionally involved and seek to make that relationship work, opposed to doing what is generally advised, ending the relationship the moment a problem occurs(on the theory that there are plenty of other women he could have anyway) rather than being a man and attempting to solve it.