Trust issues

Have you guys ever not been able to believe a word your partner says because they’ve lied SOOOOOOOO much about little and big shit in the past?? I’m talking like if he says he’s going to the gas station I’ll think he’s going to another woman’s house... because something similar has happened before and I forgave like a dummy. He tried to convince me all the time he’s not the same person but when you’ve witnessed someone tell the most elaborate lies to your face with no remorse ... it’s just hard to even let your guard down long enough to just chill out. Idk how to leave because I love him and it’s not like I can prove if he’s lying so I wouldn’t want to leave for “no reason” ?? But I feel like the way I’m feeling right now is enough reason to leave.. i guess it’s courage I lack