<human>: Can you give me the gist of the text in a nutshell?

So I am here to ask two things really: 

1. How do you learn to TRUST? I mean, young love rarely ever lasts, it's almost like people go in just for the experience. For example my last relationship, I went in there deliberately trying to just keep everything light and fun, and not get too emotionally attached (as a rule, I find emotional attachment to people is dangerous and compromises your goals, self-control and resilience. Or love makes you weak.) Unfortunately I fell in love, that made me weak, then I got my heart-broken. I forgot how social interaction leaves you prone to vulnerability, I was foolish, I will keep myself distanced in future. 

2. How do you actually get to the point where you literally do not give a SHIT if your partner walks away? I'm talking you've been with them for 5 years, you're about to propose, but if they dump you tomorrow you'll just suck it up over a few beers and move on the next day. Once they say No you walk away and it's like they never existed. No sense of loss, no heartache, no self-pitying crying or whatever, just eh it happens, that's life innit. 

I want to be THAT strong because I believe that is the only way. At least until I am 25. (I have no faith in 'true love' before the age of 25)

Basically I want to be hardened to the point that I just say hey, I die, you die, he got divorced, she cheated on him, they broke up after 20 years, shit happens, everyone leaves, we move forward. So that my fiancee can give me a breakup talk and I'm just like 'Hey that's cool, nice knowing you, good luck and that'.
<bot>: I wish to learn how to appear emotionally invested as if giving love (which I am), but so not-needy that I can emotionally detach myself at the moment of separation, abandonment, death etc.