In French, you don’t really say “I am in love”. To describe the state of loving someone, you can use an adjective, amoureux/se. You can fall into this state, same as in English (tomber amoureux). And you can be in the state of loving someone, être amoureux de quelqu’un.
But an equally valid way of expressing this, which you tend to find in old plays, is to use an intransitive verb. That means you don’t even need to say “I love so-and-so” – if you are some sort of tragic heroine in heavy stage make-up, you will probably announce at some stage, “j’aime!”, “I am in love with someone!”. It’s the same sort of phrase as “I know”, “I see”, “I dance”, or “I breathe”.
I like this facet of the language, because it makes love into an activity. The way British and American people tend to think about love is very restrictive, in my opinion – it usually has to be a mutual and considered emotion, which you can only express after a given amount of time. If you’ve been in a relationship for over six months or so, it is acceptable to say you are in love with someone. Any less, and you are looked on as, at best, a bit naive, at worst, criminally mad. Although Shakespeare was English, there’s a reason it’s Romeo and Juliet rather than Rodney and Julie. Love goes hand in hand with a clear union with another person – there must always be a subject and an object to it, and you can then be safely classified as being in that state.
But states are never fixed. You can fall in love, and fall out of love. J’aime, je n’aime pas. Sometimes, you just have an flash of love for someone. It might be someone you’re involved with romantically, it might be a stranger on the street, it might be someone you have known for years. It hits you for a moment, or you choose to indulge it for a few hours, then it passes.
I think this is a better way to think about love, today especially, as something unbridled, transient, fierce or gentle, but which certainly needs no flowers or cards or chocolate hearts. Love is one of many possible, finite actions, and you don’t need to attach an object to it. You can just feel it, enjoy it. Le week-end dernier, je suis allée au cinéma. Ce week-end, j’aime. Le week-end prochain, je jouerai au tennis avec mes amis. It’s not some terrifying, grasping, suffocating thing which upturns your whole essence, or binds you to someone else for as long as they’ll have you. I just completely love you, this morning. You be you, I’ll be I.