Suppose a young Jewish couple, Bob and Jane dated, and had sex. (Yes, I realize premarital sex isn't ideal under orthodox Judaism, but I am interested in the halachic and spiritual implications given that this is going on between people.) Then, they did not get married but split up and began seeing other people. The girl then got into a relationship with another guy, where they had sex. Eventually the Bob and Jane realized they actually made a mistake and really wanted to spend the rest of their lives with one another. Can they get married?
Halachically, I know that a man who has divorced his wife cannot go and re-marry her if she went and became the wife of another man in the meantime. Since so many relationships today involve sex but not marriage, I want to ask what the situation is when there was no marriage.
I understand that, in the past, sex (in fact "yihud") was one way to acquire a wife, but I don't think any rabbi today would consider a couple married because they had sex. If that would have been the case then a Jewish man would have to give his girlfriend a get when she leaves. So I do not think that particular law applies. But what does Judaism say about the situation spiritually as well as whether the couple can get married after all that?