Consider there is always something you can apologize for. Anywhere in your life where love is not as present as it once was, you can take responsibility and apologize. In our current culture so many people think that apologizing means that you are wrong and the other person is right. That is not what I am talking about. Apologizing is simply taking responsibility for what you can honestly take responsibility for, there is always something. Can you see that in almost any situation you can apologize for "not listening", for not hearing an opportunity or the real underlying communication? Start there. I also recommend letting the person know you are about to make an apology. "I would like to apologize for something", especially if there has been tension between you. I don't think saying, "I am sorry" communicates as powerfully simply because it feels a bit like you are a sorry person. Try it, see what you feel.
Remember apologizing is a tool for restoring love, opening up the flow of love in any relationship.Isn't that what we all desire?
Have a beautiful day. Love, Terces