James is a spiritual person and, when feeling anxious about their relationship with Regulus, they consult their tarot cards. They used them to gain courage to ask him out, to gain courage to kiss him the first time, etc.
For months, they've been using their tarot cards to ensure that Regulus does love them and he wouldn't react badly if they told him. One summer away from Hogwarts, with Regulus forever away in France and James up late at night, they consult the cards one more time.
They decide that they are sure, despite the cards giving them mixed messages this time and warning them not to be overbearing, that they want to tell him that they love him. They know they do. There's not a doubt about it. They've loved him for a month into their relationship, and it's going on a year now. They have to tell him.
So they text him in the middle of the night, a quick, "You don't have to say it back, but I need to tell you that I love you." And hope that their dear night-owl is asleep because he was telling them that they were exhausted earlier in the day. They immediately shut their phone off and force themself to go to sleep.
The next morning, they have a text waiting on their phone, just reading, "I love you too, you fucking idiot." And James feels like they could take on the world. But they also miss himself dearly and just want to hold and kiss their boyfriend.
