My dear lady, don't you know that when you move in with a guy (or let him move in with you), the man rarely wants to "buy the cow when he is getting the milk for FREE!" That was your first mistake in your current relationship. If you were dating instead of "shacking up", he would be happier to see you, be more attentive and romantic, and you would know that he wanted to be with you. You each would have space to be yourselves and live your own lives, and then be together at selected times for fun, dining out, movies, dancing, etc. All this falls by the wayside when you live together, because it no longer is a challenge, and MEN DO LIKE A CHALLENGE AND THE CHASE! When they know they "have you", they lose interest! You say he is "Amazing"! What is so amazing about him? I really would like to know. How did you meet him? Where? When did you decide to live with him? Is he educated? Good job? Goes to work Mon-Fri. and pays the bills? Does he help with household chores or expect you to do EVERYTHING? Is he Attractive? Clean and well-groomed? Does he drink or do drugs? All these things are important to answer. Do you keep yourself attractive, well-groomed; clean? Are you overweight or have you gained weight since you began dating? Do you dress nicely and put on make-up even when you're not going anywhere? Do you sometimes light candles and put on something sexy to create a romantic mood?
I suggest finding a good Therapist (your insurance may pay for weekly visits) if you have problems from your childhood that may be affecting your relationships. Some communities have free counseling at the Mental Health Clinic, so don't be afraid to ask or seek help. It's always good to have someone to talk to, who will help you work thru issues. Good luck, and try to show more pride and confidence in yourself and appearance, and that will help you to feel more self-assured.
All relationships need work; and a really good relationship takes work on both parts.