Fear of committment

How do I know that I have fear of commitment?

like if a boy or girl whom ever open up to you and you can not like if they say I love you and you cannot say it back you are afraid

if you try to change the topic when he.she starts to talk about falling in love, getting close, or just bonding on a diff level.
if you try to avoid her phone calls late at night b/c you know you guys are going to talk about personal things.
little things like that.