Was I a Terrible Boyfriend?

In my adult life, I haven't been the greatest boyfriend. Not the worst—certainly not malicious or abusive—but one with relationship-breaking emotional shortcomings. What's worse is that I carry a lot of guilt about it, and sometimes can't get it out of my head that I have somehow ruined my ex-girlfriends' lives. There are times that I fantasize about (consensually!) witnessing my exes having incredible, loving sex with their new partners. Maybe something about seeing their happiness would allow me to let myself off the hook, and maybe find happiness of my own.