People always talk about the security of being in a relationship, about the knowledge that someone will always be there for you and have your back etc, whereas I think relationships are quite the opposite of secure, you’re putting your happiness, hopes and dreams in the hands of one person who could pull the rug from underneath you and walk away tomorrow.
This is spot on.
But also I think being in a series of LTRs doesn't do much for your personality or character. To truly know yourself and what you really like, deep down, you have to have spent a decent chunk of time alone.
I have known a lot of women in my life who have just got lost in marriage: they have become so wrapped up in being wives, mothers, carers and facilitators that they haven't had time to think and be for themselves for so long and they've lost the muscle. Some of these women have just started to emerge from these marriages (late 40s/early 50s) and they are like butterflies coming out of chrysalises. They are discovering hobbies and interests and opinions that they just didn't have time for when they were busy being wives and mothers and are developing themselves in a way which is wonderful to behold.
Part of that is time, obviously. If you have small children, and particularly if you also have a job, you just don't have time or energy to do much. But its also the deadening effect of having to tailor yourself to a man and his needs and expectations.
It's so rare IMHO to find men who genuinely want their partners to be all they can be. Most of them are threatened by women who want to fill their time with interests, hobbies, socialising and travel beyond a certain point. They expect the marriage and children to be enough to sustain them. Even the relatively progressive ones seem not to encourage their womenfolk to be the best they can be.
There are exceptions to this but in my experience this is frighteningly common. And women just get tired of this and want to branch out and be themselves again.