It was a difficult marriage right from the start because of their contrasting schedules. Desi was an orchestra leader and nightclub dancer and he worked from night till morning; on the other hand, Lucille was a Hollywood actress who worked from 6am to 6pm.
Like Lucy once said in an interview, "you cannot have babies over the telephone. You just can't do that."
However, when their lives were so intertwined throughout 6 seasons of I Love Lucy, they were around each other too much that their temperamental personalities and fiery tempers came between them, not to mention the stress that they had to face.
The marriage was doomed either way. As we all know, you can't spend too little or too much time with anyone. There needs to be a balance between. It's just that people in the 20th century didn't know that, neither did they know how to handle such problems nor talked about them.