Engaged after 3 months? 🤔

So ladies, vent and opinion time. My best friend of 15 years just got proposed to last month after dating this guy for only 3 months. He is an active duty marine living on base, an approximate 4-4.5 hour drive from where she lives. They can only spend weekends together. He bought a ring 2 sizes too big, still too big even with a spacer 🙄😬 Every week he is in an argument with someone in his family. 😒 My friend and him had their first argument after 2 months of dating. He is a “recovering alcoholic” who still drinks... He has shared sexual and demeaning things on Facebook that made her upset and uncomfortable which she talked to him about, resulting in him deleting them. I get BAD VIBES from him but I’m still trying to support her... he has already discussed living on base.... being married gets him out of the barracks with benefits. He proposed to her in his home state, 7 hours away from all of her friends and family, she had no one she loved around to celebrate with, just his family who she even said “I don’t know them though” 🙃 When they’re together he “pins her down” and takes her phone and will text whoever she’s texting pretending it’s her before saying “oh by the way its ....” 🤬 Which puts me in a position to feel like I can’t even talk to her without fear of him taking her phone. 😤 She says she’s still getting to know him and is trying to figure it all out. I told her I don’t think she understands she said yes to forever with him so if he’s already causing this many issues only 4 months in and is trying to move fast... then how would marriage be... She says he makes her happy yet he got involved in an argument with her parents and yelled at them to shut up... disrespectful... 😱

So in conclusion, I don’t know how to be a supportive friend when this guy is nothing but RED FLAGS because I’m always honest and don’t know how to not be one of those “walk away” people... 😭 HELP 🤕

PS: I was in an emotionally abusive relationship in the past so I recognize the signs, this is her first REAL relationship... my mother was in an abusive marriage and one our mutual friends is a divorcee from an abusive (and cheater) army man, in which they were married after 6 months of dating (the path she’s headed down-quick marriage). Myself, my family, and all of our mutual friends all feel like she should not marry him but we all know that you never know until something bad happens... I’m just so concerned for her 😞 😥