(25F) and my partner is (28M) 10 years together, how to end it? How to start over?

So, my partner and I met in high school we have been together ever since. It has been 10 years, we have been living together for 6 years. I can be silly at times and my partner doesn’t seem to like it, in fact I feel awkward afterwards. I feel as if I don’t know myself anymore. I love him but I don’t know if I am in love with him anymore. We have always spilt the bills, we have bought all of our furniture in half. I am not close with my family and since we have been living together I’ve slowly lost my social life. I feel like I’m staying because of security, I cannot live with my parents or family members. I’m scared to be alone, he has been there for when I have lost my father and through toxic family interactions. We have a bond on a level of trust and support but the passion is gone, we have different views on life now that we have grown. I need advice on how to go through with how I am feeling regardless of the living situation and the lack of a support system. I’m driving myself crazy with trying to conform into the relationship but deep down I know I’m just not happy and it isn’t fair to him either. Any advice or other perspectives would be very much appreciated thank you.