Idiom request for critisizing someone who ignores or overlooks their old things or friends, in an annoying manner, after having or finding new ones

There is a quote from William Makepeace Thackeray (1811-1863) saying that:

Novelty has charms that our minds can hardly withstand.

Also, Thomas Hood (1799-1845) said:

There are three things which the public will always clamor for, sooner or later: namely, Novelty, novelty, novelty.

A new broom sweeps clean [, but an old broom knows every corner/all the corners]

Don't be in such a rush to throw away the friends or lover you have for someone new who may not be better and doesn't know you as well. Also can be applied to objects which have served you well. Don't be so quick to throw them out in favor of new but not as effective products.

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