How do men make emotional connection with their partners?

Hi all, I am not able to emotionally connect to all my last 3-4 relationships which I ended and felt nothing. I was fully invested, all in all of them but non of them made me feel emotional connection. All partners were great and the last one was so good that I had expectation of getting married to her. But this all was logical in my head, like an advocate of relationship. I was open book to all of them, have shared all my deep feelings insecurities and what not. Is it common or am I illiterate? I want to take my life to next level but this connections is missing in my life. I started believing that after marriage I will change drastically but then a friend made me realise that it doesn’t happen like that. I need help in understand what is emotional connection and how do you form that? All I have in past was just attractions and interests which faded over time. All relationships lasted for 1 year and that scares me for future.