Scarcity in my view of having a happy relationship/good available partners

I have so much doubt and fear that I will never find the “right guy”… not that he needs to be perfect, but someone who I can spend my life with and who will still want to be with me after years. I have my scholars work… I think I could love someone’s with all their flaws for years and years as long as they are faithful. But can I find someone who will feel the same about me?

I have this belief that there are “no good guys out there, and if there are, all the good ones are taken”. I have another belief that they will all either “lie, leave or be a deadbeat”. My brain tells me these things so easily, but I know there are good guys out there! My dad is a good guy. There are so many amazing fathers and husbands and boyfriends… but I don’t feel like I know any outside of my own dad, and even he and my mom have their issues.

My 2 best friends are unhappy in their relationships, and I have always ended up unhappy in the ones that I’ve had. But I want to get married one day and have a family so badly. I don’t think these beliefs are serving me.

How can I start to gather evidence to support more useful beliefs when I feel like I have so few examples of positive relationships around me?
Should I try to repeat a neutral ladder thought like “There are technically no bad guys out there” instead of “There are no good guys out there”?

This is quite daunting for me to figure out how to tackle. Thank you in advance for any advice!