"If someone said to your daughter that she wasn't pretty or interesting enough to be loved, and it made her sad and scared to get in a relationship, what would you say to her?"
I have no idea what I'd say to my daughter if someone said that to her. I can't imagine anyone saying it to her because it simply wouldn't be true.
It simply wasn't true when someone said it to you. It was only because you were so young and vulnerable, and it was said by your mother, that you believed it and internalised it. Here you are, feeling the impact of that lie so many years later.
Congratulations on breaking the pattern and bringing up your own DD so differently.
There is some work for you to do on the unloved child which you used to be. I so hope that you find what you need to do that.
How much of your history is your inamorato aware of? Does he know any of your dilemma about never having felt loved?
It might be difficult for him to hear that you doubt his motivation for some of his actions.
Everyone is different but ... I tend towards showing love to DH rather than saying it.
The things you describe that he does are exactly the things I would do and would want him to know that's love. It would feel quite hurtful if you misunderstood that, explaining it away by saying he is just a decent person or something like that.
The only way to learn these differences is to talk to each other about what things feel like to you. Taking responsibility for your feeling and explaining them to each other.
It's taken a while for DH and I to do this, in order to understand how we each show love. The worst disagreements we have ever had have been when we misunderstand each other's motives but once we worked through it, it meant that we understand each other much better.
I dearly hope you get to have these conversations.