That’s because you came across the wrong type of fake boob. On a decent boob job you would not be able to tell they are fake. First and foremost they are the right size for the body, not too big not too small for the gram (can’t put Ds on a 5’2”). Then it has to be done so the shape comes out right and incision is not very visible until close inspection.

A boob like that would look and feel very natural.

I am also assuming you are young and have not been in relationships where your partner has given birth or boobs naturally became to sag, where implants would significantly improve both the look and the confidence of your partner. Or a partner with uneven boobs, needs boob reconstruction or has significant self esteem issues because of their boobs. I think if you had been in any of those relationships you would not say “fake boobs are no go for me”.

In general if you are saying “this physical trait is a no go for me” you are just fooling yourself because at some point in your life you will meet someone that is amazing and compatible in every aspect with you but has that physical trait you said you would not accept. At that point you will realize how silly and immature it sounds to write off someone because of a physical characteristic. The only things that truly matter and keep a relationship alive are personality compatibility and character. The rest always fades