So my best friend, who I care about more than anyone else in my life, keeps getting himself into these toxic relationships with girls and I really want to understand why so that I can try to help him.

So he's 21 and he's only had one girlfriend freshman year of high school. After that year he moved to another state and broke up with her. These weird relationships began about 2 years later as far as I'm aware.

First came the girl he took to prom. He later agreed with me that we both knew from the very start that she was out of his league and that he was deep in the friendzone. He knew from day 1 that he would never date her but for over a year he pursued her, tried to hang out with her constantly and she always had excuses like "I'm not feeling well" and "I hate the movies" The whole time he kept saying he wasn't fully asking her out because he was waiting for her to graduate high school. eventually he found out she had gotten a boyfriend and he moved on.

A few months later he met an Arab girl at school who instantly showed interest in him. He was apprehensive but liked her. Thing is, we both knew they would never date because her religion and family forbade it. This whole time his stress levels went sky high, so far as having a full blown panic attack at school. I believe the stress was mostly caused by this relationship. We also questioned whether she truly liked him of was just lusting. After a couple of months this was confirmed as she started drifting away and caring less. It became obvious that she was just keeping him around for homework help on an elective class she took that only he understood. However he kept obsessing and texting her every single day trying to keep their pretend relationship going. After they finished that semester she quit talking to him completely and she was never mentioned again. He had wasted around 10 months on her.

Finally, a few months later, he decided to bring back an old mutual friend we both met gaming years ago. We hadn't spoken to her in 2 years and he brought her back out of the blue, and instantly began obsessing over her. He has talked to her non stop on a daily basis since January, and is basically acting the same way he acted with the Arab girl. Thing is, we also know he'll never date this girl as she's autistic, has a ton of mental health issues (as my friend put it "way too many to deal with") is very depressed and above all else lives in Australia. We're in the US. This hasn't stopped him from obsessing over her. As she's a mutual friend I think he's ashamed so he tries to keep their pretend relationship secret. He constantly lies and manipulates the situation to pretend nothing is happening even though it's clear there is something. For example he even stays up really late waiting for me to go to bed so he can call her and talk to her. (I've noticed by going to the kitchen to get water late at night and hearing him or seeing his headset plugged into his computer the next day) He's constantly stressed and even paranoid of the whole thing and has mood swings dependent on how much he's talking to her, tends to be happier when they talk less. This also happened with the Arab girl. I'm also worried about the girl as she's so unstable that when he eventually moves on it may really hurt her and make her depression that much worse.

During this whole time he hasn't had an actual relationship. His pattern seems to be:

Find a girl he knows he cant date.

Obsess over her, spending morning to evening talking to her.

Getting as close to a relationship as possible without actually dating. Meanwhile getting stressed and anxious about the whole thing.

Finally moving on almost a year later. Is truly happy for a few months with no worries.

Wait a few months, rinse and repeat.

Meanwhile, he's had a couple or opportunities to actually date girls that like him and he's turned them away or avoided the whole situation entirely.

I really wish I could understand what's going on because I want to help him, I just can't and he won't let me. My theory is that he's suppressing something deep inside that he may not even be aware of and its affecting his relationships. He wants to be with someone, but cant commit so he gets to it as close as he can without actually getting to that point and plays it safe by only doing this with girls he knows he cant date.

Please let me know what you think is going on and what I could possibly do to help. How can I approach this with him without making him mad. He has accused me in the past of being jealous when I am just trying to help him.