I agree with what you said about the influence of the past. But maybe this ^^^^has something to do with your feelings for Roberto. I could be way off here but the way you've described it makes that steady, devoted attachment almost sound.... boring?

Even his name (pseudonym?) makes me think of something exotic... tango maybe.. passion... moonlit beaches!

Could you be discounting the reasons that your partner is with you? You might be the kind of person who makes him want to tango! Maybe it might be possible to rekindle that in your relationship.