This sounds like a classic "Consequentialist vs. Deontologist" dilemma. A consequentialist defines morally right action as whatever produces the best consequences. In this case, you predict that the best consequences will be produced by keeping your infidelity to yourself and resolving never to do it again. But a deontologist defines morally right action as whatever is required by duty, and if someone has a right, then there is a correlative duty binding someone somewhere. In this case, you acknowledge that your girlfriend has a right to know, which would entail your duty to tell her. So the consequentialist "right thing" and the deontological "right thing" are at odds. Or are they? Perhaps your predicted consequences are incorrect. Your girlfriend may find out without you telling her, especially if several friends think she should know (things like this do happen, and not just in the movies). Then in addition to being crushed by your infidelity, she will be further hurt and alienated by your...

Sure, I think there's a parallel, particularly if you consider that a person is not an isolated, self-contained entity, but rather a being-in-relation. Your identity is defined partly by your relationships with particular others, and the more intimate the relationship, the more it contributes to your identity. Intimacy is a matter of sharing first-person perspectives (what the world looks like from your eyes is shared with your intimate, and what the world looks like from hers is shared with you) as well as plans, goals, projects, etc. In fact, in a truly intimate relationship, you'll adopt the plans, goals, projects, etc. of your intimate as your own. When the relationship ends, especially if it is ended unilaterally, all of this that had been part of you is to some extent alienated, which would suggest that your identity is changed. The person you were, in intimate relation with that particular other, doesn't exist anymore. So it is, in an analogous sense, a death. But it's not as complete...

Whether an act is moral or immoral will vary depending on the moral system that's assumed. For example, some people think morality is matter of doing one's duty, while others think it is a matter of the best overall consequences, or of building a virtuous character, and so on. I'm not suggesting that all of these moral systems are equal, but they do lead to different answers, and which system is better is a different question (a meta-ethical question) than whether a given act is moral or immoral. That being said, most moral systems would recommend the husband in this scenario not tell his wife. Confession may be good for the soul, but it's not an end in itself. It's a means to something else of moral worth: duty to God, perhaps, or character-building, or good consequences. In the absence of these ends, confession seems to be a rather selfish act. One consideration in assessing the morality of this confession would surely be whether the wife ought to know: does she have a right to this...