I remember I once knew a boy who was deep in love with Rainbow Dash. It was during the height of the fandom, when I was like 16-17 and he a few years younger.
His avatar immediately stood out since it was a love confession to Rainbow Dash, as well as his signature. He constantly confessed his love to RD. This was when I was new in the fandom and the whole concept of waifus was alien to me. I thought he was joking (like I assumed all other previous instances where I heard of waifus to be jokes and roleplaying). So I just asked him in a private conversation. And yeah, he was serious but it took me some time and repeated confessions on his side to realise it.
He said his real life sucked, MLP gave him hope and his love for Rainbow Dash was the only thing keeping him going. At one point, I asked him: "Pal, do you live only for a fictional cartoon pony?"
And he was like: "Yeah, that's how it is, but I see no reason why it shouldn't be this way. My real life is NOTHING to me. If there is that pony dreamworld where I have someone I love and who gives me hope - why not? DASHIE MY DEAR I LOVE YOU!!!"
Then I asked him jokingly "Sure, but, for real: Does RD love you too?"
He was like: "Please, please, not that topic [if RD can love him back]. I... I tried to cut my veins because of this."
I was like: "Bro, you need help! A cartoon pony is not worth dying over. Also it won't solve your problem [that your real life sucks, you're in love with RD but can't get into a relationship due to her being not here]."
So he explained: "Why not, then I can finally meet RD in Heaven."
Me: "What the heck?!?"
Him: "Well Heaven is supposed to be the perfect place, and that is subjective. So my perfect place would be me living as my ponysona with Dashie together in Equestria."
Then I explained that suicide is a sin and that even for me, as a very educated, open-minded and tolerant person, the whole idea of meeting a cartoon pony in the afterlife sounded very strange. I don't remember how but I managed to talk him out of his suicidal thoughts. He mentioned a girl at his school and I convinced him to try talk to her. In the end, he said that he still loves RD and will forever love her and also believes he will meet her in Heaven. But he will never commit suicide and live his life in the Human Realm to the fullest until then.
A few years later, he stopped loving RD though and also lost interest in MLP and Bronies. He reflected back on that time and explained that his life used to suck but when he discovered MLP and Bronies it gave him hope. He fell deep in love with Rainbow Dash, but it was two-sided: It gave him hope and at some points only his love for Dashie kept him going, but also it drove him down cause he couldn't actually get into a relationship with RD, cause, y'know she's a cartoon pony.
Some time even later, I contacted him again and he said he thinks MLP is only for kids, that Bronies are ridiculous and he's ashamed to have been one.