I kept going back and forth about this and ended up ordering one size up. Cartier suggests to do so in their online shop. But I also contacted customer service and got told to order the same size in the love as in the trinity.
In the end I'm really happy that I went one size up because I can wear the love ring on different fingers and also stack it with the trinity. If I would wear it instead of the trinity on the same finger, the same size as the trinity would be better.