I don’t get that “bad person” vibe off him like other toxic people I’ve met.  He has said he knows he’s not perfect [despite always joking he’s never made a mistake] and he wants us to tell him when he can improve.

I have heard from a lot of people, including my fiance, they suspect he’s trying to break us up. I highly doubt that mostly because I have such a low sense of self-worth I doubt anyone as attractive and charming as him [because he is, there’s a lot of girls who have crushes on him, but he’s convinced he’s ugly and nobody likes him] would actively pursue someone like me.

I’m quoting these two things you said above because they’re important and relevant with each other. Do you think the fact that this attractive and charming man paying so much attention to you may be clouding your judgment a bit?  I don’t like to throw the word “narcissist” around, mainly because I think it’s vastly overused this day and age, but from what you’ve described so far, he is sounding pretty textbook narcissist, which means he knows what to say and how to say it to get you to trust him, even when his actions should be speaking louder than his words. It’s a deception but people constantly fall for it because of the charm. That’s why I definitely think it’s important to pay very close attention to how he treats others because he WILL treat you that way sooner or later, now matter how he treats you right now.

while I’m the only one he’s given back rubs and played footsies with [I’ve asked them] if he knows you’re comfortable hugging him, he’ll hold your hand or accidentally brush against you a little more than coincidentally.

How does your fiance feel about him doing these things to you, and how would you feel if another woman were doing this to your fiance? It’s important to note this because it’s a gray area when it comes to infidelity with some people, although some people are okay with these kinds of things, many will find it inappropriate and leaning toward disloyalty. If either one of you would not be okay with the other receiving this kind of treatment for someone else, that’s another red flag toward your friendship with this man. It could be damaging to what I assume is a relationship that is very important to you (I’m assuming so because you’ve agreed to marry your fiance). If your fiance would be bothered by it, is it worth the damage? Also, how does HIS girlfriend feel about it?

I feel it’s all his perception of himself and I’m hoping to talk to him [but I’m not sure how to word it] so we can work together to improve his “alpha” persona when he’s in public. He tells me frequently how he’s the master of perfect first impressions and he’s terrified he’ll never live up to that first impression so he goes extra with everything. I can’t tell you the number of times we’re in a group and when the two of us leave to head home you can see him physically drop and breathe a sigh of relief and he turns into this completely different person who is anxious and sweet and tranquil.

Do you think the fact that he appears to act differently ONLY around you might be helping you make excuses for his behavior, thinking he’s misunderstood and only reacting that way because he’s insecure, so if only he could feel more secure he’d act differently and everyone would see what you see and that you can help “fix” him? That can be a trick, too. It’s a way to get you to let your guard down. Narcissists tend to build people up, make them feel special, like a million bucks, until they know they have them and then they flip. I’m not saying he’s definitely a narcissistic person or even that he’s being calculating for sure, because there’s no way for me to know that, I just want you to make sure you keep your eyes wide open. Read up on narcissistic abuse, how those relationships start (even friendships), what happens during, and what happens after things start changing (which usually happens so gradually that you don’t notice it happening until suddenly you feel terrible about yourself and you’re isolated from all of your loved ones and yet can’t understand why you feel so badly).  I’ve been through it in way, so just read up on it so you’re aware of what goes on so that you can see the signs if they’re there, and don’t let his charming nature cloud any judgment (we as people in general tend to make excuses for charming and attractive people for behavior that shouldn’t be excused, because their charm blinds us and makes us think they must really have good intentions. That’s how narcissists are able to do what they do to people. My daughter’s father is that way and it’s hell trying to coparent with him sometimes. lol).  So just read up, stay educated on that kind of a person, and pay close attention for annnnyyyy red flags without excusing behavior… and that will help you protect yourself from falling into narcissistic abuse. From what you’ve described of the advice your friends have given you, I’m pretty sure that’s what they’re worried about, too.