How do you say it must be love in french?

There are a few ways to say "it must be love" in French, depending on the level of formality and the context. Here are some options:

Formal:

* Ce doit être l'amour. (This is the most literal translation)

* Il ne peut s'agir que de l'amour. (It can only be love)

Informal:

* C'est l'amour! (This is the most common way to say it in everyday French)

* Ça doit être l'amour! (This is slightly more informal than "ce doit être l'amour")

* J'ai l'impression d'être tombé amoureux! (I have the feeling I've fallen in love!)

The best option will depend on the specific situation.