I think it's true actually. In my case I met my exh at 18, (after a difficult childhood with an NPD mother), and was so grateful for the love that I spent the next 25 years moulding myself into the person I thought he wanted, and ended up miserable and depressed because of it.
I left (long story), and entered into a three year on/off relationship where I spent the time trying to be the person I thought he wanted, in the process I lost the person he was attracted to in the first place!
It's taken me quite a while to figure out who 'I' am without someone else's expectations. eg, I like to write, that's my real hobby, it's not DIY, or house remodelling, or sport, or triathlons - although I can do all of those and enjoy them, I write.
I'm now at a stage where I think I'm ready to date again. I saw someone for three months recently. Whilst it was lovely and he was a really nice person, there were some fundamental things that I was compromising on that I knew meant it wouldn't work and so I ended it. I did start to go through the 'present myself as the person he wants' phase though - but recognised it early enough to stop it this time.
That was a bit long - sorry 