Have you had serious relationships in the past?
ai a-VU-to STO-rie SE-rie in pas-SA-to — stress on 'vu-', 'sto-', 'se-', 'sa-'. 'Serie' has two syllables: SE-rie.
A more personal question — appropriate when both people are comfortable and seem genuinely interested in each other's history.
'Hai avuto' = you have had (passato prossimo of 'avere'). 'Storie serie' = serious relationships ('storia' in the romantic sense means relationship/story). 'In passato' = in the past. Asking this shows genuine curiosity about someone's relational history.
Sei mai stato/a in una relazione lunga?
Have you ever been in a long relationship?
Specific about duration — practical and revealing
Come sei uscito/a dalla tua ultima relazione?
How did you come out of your last relationship?
Goes deeper — emotional maturity is revealed in how someone discusses past relationships
Quanto tempo è che sei single?
How long have you been single?
Direct and practical — good to know to understand timing and readiness
Italians tend to have fewer but longer relationships — a three or four year relationship is very common before marriage or long-term cohabitation. Discussing past relationships with maturity and without bitterness ('di comune accordo') is a very good sign and appreciated on a first date.