How long can infatuation last?

Lifetimes.

About a year. A chemical called phenylethylamine (I think that’s the correct spelling) is released into the system when you’re infatuated with someone so that you’ll make lots and lots of babies. But, once those babies are born, your body naturally needs to calm down so that you can stop thinking about yourself and your new lover and get down to the business of child-rearing.

Love, appreciation, and attraction to a partner, on the other hand, can last a lifetime.

I agree with @absalom
Lust is what fades in the way @borderline_blonde was describing. It’s dopamine, norepinephidrine, phenylethylamine (PEA) and serotonin that all cause the lust

Just sayin’, I’ve been infatuated with the same guy for four years now. But we never got married and had babies together, so maybe that’s why.

If it is just infatuation then my answer would be out of sight, out of mind.

I think lust and infatuation are very similar except that lust is more sexual whilst infatuation is more emotional. So I think infatuation lasts longer. I would say lust lasts for months whereas infatuation usually lasts a year or two.