It's obviously a psychological crutch of some sort. There is no data to suggest that spinach has any addictive potential in and of itself. However, if Popeye believes that it gives him strength and he must if he has been using this for so long, then of course, it will. Mind over matter with the help of spinach. It is clear to me that Popeye and Olive Oyl have a lot of emotional baggage to overcome.
Any couple needs to make a commitment to working on their marriage.
After all, this couple has been a couple for over 70 years so they must have been doing some things to maintain that relationship. It is common for couples to stop paying attention to the relationship after they are married. By this I mean, they should take time to be together and share in positive common experiences, just like dates. They should give time and relationship issues as much priority as career, exercising, being out with the boys, etc. And they should learn to respect each other's feelings.