Having LTRs is fine imo as long as you stay the same person you were before. A lot of guys make the mistake of falling into one-itis and becoming too emotionally attached. Once you're emotionally attached to a girl, it becomes hard to pass her shit tests, it becomes harder to say no, it becomes easy to just let yourself go. Over the course of several years, this slow mutation of your personality turns you into (and her) into completely different people.
You have to realize that this can happen by no fault of the girl. It's just that the guy has allowed himself to get lazy and passive.
Paradoxically, the better the girl is, the harder it is for the guy to avoid this, and the probability of disaster increases. It might actually be better for an LTR to avoid 'perfect' girls and instead stick with someone with lower desirability. That way, you never get too attached and can leave if you want, and when she knows that, she will try harder to please you and make you stay.
You have to realize that this can happen by no fault of the girl. It's just that the guy has allowed himself to get lazy and passive.
Paradoxically, the better the girl is, the harder it is for the guy to avoid this, and the probability of disaster increases. It might actually be better for an LTR to avoid 'perfect' girls and instead stick with someone with lower desirability. That way, you never get too attached and can leave if you want, and when she knows that, she will try harder to please you and make you stay.