My friend's 8-year relationship ended when his girlfriend monkey-branched to another guy in 15 days. Now she's giving mixed signals after the rebound crashed in 4 months. Am I crazy for thinking she might come back?

Throwaway for obvious reasons. My close friend (23M) was in an 8-year relationship with his girlfriend (23F) starting from when they were 14-15. It was intense — they spent 10 hours a day together, had sex ~2000 times (mostly sneaking around because her parents were extremely strict — her dad once beat him badly and almost used a knife, but he still stayed). He was incredibly loyal, rejected 10 other girls, stayed through everything, and was basically the "perfect" supportive boyfriend (high achiever academically, emotionally mature, high EQ, etc.).About 5 months ago, while she was in another city and he was supposed to join her soon, she started talking to a guy who had proposed to her multiple times over 9 years. She cheated, replaced my friend in just 15 days, and told him she was in love with the new guy. She was extremely sure — said things like "this is real love," discussed baby names after 2 days, tagged him in stories, etc. She cried a lot during the cheating phase and for ~50 days after, but still didn't come back even when my friend begged for 115 days and was suicidal.
Fast forward: The new relationship lasted only 4 months. She told my friend they broke up a month ago and "stopped talking" except for one recent accident situation where she helped the new guy with police/bike stuff, ended up in hospital with severe cramps (possibly from i-pills taken earlier). She insists they are not together anymore and last had sex over a month ago. Now she's giving my friend very mixed signals:

• She volunteers details about the new guy situation (hospital, i-pills, accident).
• Says "hm sad ya" to old happy videos he sends.
• Doesn't fully block or ghost him.
• But replies minimally/coldly ("ya", "no I don't want anything", "why do you wanna meet?").
• Refuses to unblock him everywhere because "you'll start spamming asking me to come back."
• When he begs to save the relationship she says flat "No" and "it's not worth it."

My friend is spiralling hard — feeling like he wasn't good enough, maybe he lacked physically, etc. He's super resilient (top student, state-level player, high IQ, loyal as hell) but this is destroying him.I (his female friend) have been talking to him a lot. From everything she's said and done, it feels like classic fearful-avoidant push-pull: she runs when things get too real/deep, but the anxious side keeps leaking back toward my friend.Question for you all:

• Is this typical fearful-avoidant behaviour after a rebound crash, or am I coping too hard?
• Does the "calm" end with new guy (only 4 months, now just "complicated ex" help) mean the feelings for my friend are still there under the walls?
• What are the realistic chances she comes back (even messily)?
• Advice for my friend on whether he should keep hoping/low-contact/pull back completely?

I know it's a long read, but we've been living this for 5+ months and it's genuinely confusing. Any perspective (especially from people who have been the dumper or dumpee in similar situations) would help a lot. Thanks.