I once wrote a post on philophobia. For a long time in my life I was unable to allow myself love. Philophobia can be caused by a lot of things. It could be due to a previous heartbreak or an even that occured in the past etc but the good news is, it is possible to get over such immense fear. However, you cannot do it alone, you need someone who is willing to understand and take it easy with you through the steps but it starts with you willing to try. You can always research on it and read up more about it.