Are men so lonely they will almost date anyone (for a short period)?

I have noticed that most men are so lonely, that they will become quickly attached to me in the beginning, but not be able put in the effort for a long term serious relationship.

I (36F) am a pretty confident, attractive, fit, cheerful and friendly person. I usually date people around 28-32 age range.

I have noticed that it is easy for me to find a boyfriend (usually a nerd / introvert because they're my type) simply by showing genuine interest, initiating contact, being sweet, being open and vulnerable, listening to them, and being interested in their life.

I find myself falling in love with them, and they usually fall in love with me pretty quickly.

I used to believe they were reciprocating my feelings because they truly like me for who I am and wanted a relationship with me. But I have noticed that after about 2-6 months, many of my boyfriends decide they are either not ready for a serious commitment, start to doubt the relationship, start to mistreat me, or they realise I am the wrong person for them and they want to be friends. In the meantime, I am still in love with them.

It makes me think that the reason many (not all) of my pevious partners fell so hard for me in the first place is simply because (1) I was there (2) I showed interest (3) I'm pretty (4) they are lonely.

I am disappointed and hurt to realise this and it makes me question all of my past relationships (there have been many). Does this theory resonate with anyone else? How can I be sure that the next person I date genuinely wants me for me, and not because I charmed them into a relationship? How do I make sure they want long term with me?

Thank you

Update: I appreciate everyone who gave their honest perspective, even the mean comments. I have a lot to think about. I promise my intentions in a relationship are always to find love and I try my best to make good choices. But we can’t always help who we fall in love with.