Even if there are no detectives or binoculars, partners can still use technology to spy. Snooping is a breeze in this age of iPhones, emails, and Google.
Leos are insecure, so they want to get attention and be seen as good. If you don't like your partner, you might start to suspect them and check their phone
Perfectionism can make it hard for Virgo to trust people. They like schedules and routines, and if their partner is even a little bit different
Geminis are social and like to ask a lot of questions. Because they have two personalities, they can be suspicious of their partners.
Taurus is loyal and down-to-earth, and they like relationships that are stable. But jealousy and possessiveness can make partners spy on each other.
Sensitive Cancer's emotional nature can make it hard for them to trust their partners, which can make them feel anxious and overthink
Scorpios are natural detectives, but they don't trust other people because they are emotionally weak. They care a lot about their partners