Your description is difficult to understand. Did some random guy accuse you of cheating on your Taurus? Or did some random guy accuse your Taurus of cheating on you?
**If he accused you of cheating: It's cut & dry. Your Taurus can't take cheating. There is no real way for him to prove that you did not cheat. He can't live with doubts, suspicion, or paranoia. So he has to break off the relationship on principle. The one & only thing this guy NEEDS in a relationship is faithfulness. If anyone accuses his girl - it doesn't matter if she is innocent or guilty. It literally cannot be proved, so he HAS to let her go. No matter how much it hurts him or his partner or his kids. It's just the way it is. Accept it. Perhaps you could point out that it's some random guy. Perhaps you turned some guy down, or didn't flirt with him & he got jealous. So he started spreading rumors about you. That happens all the time. A guy can't sleep with you, so he ruins your relationship. He hopes your boyfriend is insecure, and he will play on it. It's a cruel, evil thing. But it happens all the time.
**If he accused your Taurus of cheating: It's simple. Your guy did cheat on you. For whatever reason this random stranger felt the need to tell you. Who knows maybe the guy is his friend & he can't stand seeing his friend behave so lowly, or maybe he was being inappropriate at work, whatever. You should just be glad this person told you he was cheating. Take it seriously. But also consider, this person could want your relationship to end so he has a chance (or a friend). That does happen as well, but it's less likely.
Your Taurus felt super insecure when you confronted him. & he had good reason to be - he's a cheater. He was angry. It's because you questioned him. In his mind this is you not trusting him. In other words, he knows you suspect him. This makes him even more nervous. He wants to beat up this guy b/c this dude blew his cover.
Taurus does not like being the 'bad' partner. So he has to do everything in his power to appear innocent. Especially to his next partner. He will do anything to flip the situation on you. Your Taurus cannot survive in a relationship where he is paranoid. If you even suspect him of cheating he will feel paranoid. Even if you don't take it seriously, he's worried it will come up in the future. So he has to break off the relationship no matter what. He's going to make you think you did something wrong, so that he can appear innocent.
You were not disrespecting him with other men. He was disrespecting you with other women, and a guy came to tell you about it. You must realize this. Your Taurus is going to ignore you now, b/c he thinks you believe his b.s.
His goal is to appear innocent, preserve his reputation, & make you think you did something wrong. Don't allow him to do this. Realize he cheated. He had no way to back out of the relationship without admitting his guilt. So he blew up on you. He flipped it & tried to make you believe you did something - anything - wrong. Now he will quietly disappear. There's nothing you can do about it. And you should let him go. Good riddance! You don't need a cheater in your life, or even a man whose been accused of cheating that is willing to blow up on you if he was innocent. You need someone who is mature & with an even temper. Certainly not someone who is going to beat someone up and resort to violence just because they spread a rumor. That's just childish. Think of that kid in the classroom, "But they were talking about me..." wahh. You don't want a husband/boyfriend whose cut from that cloth. Can't raise children if your husband needs to be raised along side them.
& of course he keeps a record of when you 'disrespect' him, but doesn't account for his own mistakes. You understand there are plenty of selfish, unfair, hypocritical people out there. If you have a man that thinks he's holier than thou and can do no wrong it's going to be a rough relationship. i don't think he's ready for marriage anyway. A man needs to admit his mistakes to be able to overcome relationship barriers/issues. If he can't do this you will suffer for it. I understand you have spent a lot of time with this guy & have a bond. But honestly if you met a man who really treated you fairly & with a level head you would be so much happier. I think you should consider dating other men. You'll have to weed through a lot of jerks to be sure, but it's worth waiting for someone who can really care for you. Besides, if you were accused & he really pulled this crap it just shows his lack of trust. His unwillingness to get to the bottom of the matter & confront the accuser. Even then he should at least sit down and consider, if you did cheat on him...could he forgive you. No person should get married if they can't forgive their spouse for cheating. It's setting yourself up for divorce in the future, especially when you consider the infidelity statistics by country. Cheating is a common occurrence in a marriage. If your fiancee cannot accept those facts, look at you, & say "well, I still love you & want to spend my life with you, let's work on this together." He really isn't a good candidate for a husband. Granted no one should enable or condone cheating. But if he can't forgive you, give you a chance, or even investigate the matter - this guy isn't worth it. & if he is the accused you should be investigating the matter further, but if he's not speaking to you & he did what he did it's very good evidence that he was actually cheating. He's too guilty & worried to reveal himself to you or continue to look you in the face and lie every day. Who knows maybe he's been waiting for an out from the relationship for quite some time now.
I'm sorry to hear about this! I hope this helps! Sorry I couldn't understand your question fully, but I hope the answer I provided for either scenario is sufficient.
Student of Astrology