Jealousy arrives as certainty, which is what makes it so hard to think about. It feels like knowledge rather than a feeling, and it is almost always the second one.
Ask what it is pointing at
Often it is not about the other person at all. It is about time, attention, or something unsaid that has been building for weeks.
Say it early and small
Named at the time, jealousy is a manageable sentence. Left alone for a month it turns into an accusation, and then a fight about the accusation.
Reassurance works, surveillance does not
Checking phones has never once settled anything. Consistency over time is the only thing that actually reduces it.
Recurring jealousy is its own problem
If it keeps arriving regardless of what your partner does, it is not being caused by them, and treating it as if it is will exhaust you both.