I think we are good together.
PEN-so ke STA-mo BE-ne in-SIE-me — stress on 'pen-', 'sta-', 'be-', 'sie-'. 'Insieme' has three syllables.
Expressing positive assessment of the relationship — a warm and affirming statement.
'Penso che stiamo bene' = I think we are doing well (presente after 'penso che' — contemporary Italian increasingly uses indicative). 'Insieme' = together. This simple sentence affirms the relationship as functional and good.
Mi sento bene con te — è una cosa rara.
I feel good with you — that's a rare thing.
Acknowledging rarity — this quality of feeling is not taken for granted
Con te le cose hanno senso.
With you things make sense.
Meaning-making through relationship — philosophical and warm
Non ci manca niente — abbiamo tutto quello che serve.
We lack nothing — we have everything we need.
Completeness — the relationship is sufficient
Italian relationship culture values the explicit affirmation of what is working, not just the discussion of what is not. 'Le cose belle vanno dette' (good things should be said) is a philosophy of relational maintenance — appreciation expressed regularly keeps relationships healthy.