Why won't my man commit after all these years?

I have a 4 year old for a man I have known for over 20 years. I have two older children for a previous relationship. I have history with my younget childs father and had split up from the older childrens father and had been on my own for over four years before getting involved with him. He has been a goood influence to my older children, a good father to my youngest yet he is very secretative about his life, will not invite me to his house although he lives alone; will not invite me to meet his mother.

I am a teacher and own two homes. I am 43 and fairly attractive. I do not know what the problem is.I recently moved and have not allowed him to come around in order to spite the way he treats me. We do stillsee each other and he has stated to try and improve the relationship by taking me out. I still do not feel like we are moving forward. when ever I try to speak to me me does not say much. I can feel some kind of love, seeing that we started seeing each other in 1983 and things are still hot been us - why wont he commit?