I received an anonymous message saying my boyfriend cheats, but it included no proof and one detail only a friend would know

On Tuesday night, a new social media account sent me one sentence: ‘You should ask your boyfriend what he really does after basketball.’

There was no name, photo or follow-up. When I asked what they meant, the account disappeared.

My boyfriend plays pickup basketball on Wednesday evenings at a community center. He usually leaves around six and gets home before ten. Sometimes the group gets food afterward. I have met several of the people he plays with. Nothing about the routine has ever seemed secret.

The message would have been easy to dismiss except for the word ‘basketball.’ He does not post about it. Most of my coworkers do not know he plays. The detail narrows the sender to someone who knows us, or someone who knows someone who knows us.

I showed him the message the next morning. His first reaction was confusion. His second was anger. He handed me his phone and said I could look at anything. I did not take it.

He thinks one of my friends sent it because two of them have never liked him. I think accusing my friends with no evidence is exactly what the anonymous person may have wanted. We spent an hour listing people who could know his schedule and made ourselves suspicious of everyone.

Then he asked whether I believed the message.

I said I did not know. That answer hurt him more than I expected. He said four years of being trustworthy should outweigh one sentence from an empty account. I said trust is why I showed him instead of investigating behind his back.

Since then, Wednesday has become unbearable. I notice when he leaves five minutes early. I notice whether he showers before going. I hate the version of myself who is recording these details, and I hate that someone created her with twelve words.

My boyfriend offered to skip basketball for a while or call me from the gym. I do not want that. If he is faithful, those measures punish him and turn our relationship into a performance for an anonymous stranger. If he is not, a few calls would prove nothing.

A close friend told me to message everyone in the basketball group quietly. Another said the absence of evidence means I should delete the message and refuse to give it a second life. Both options feel extreme.

There is also the possibility that the sender was warning me badly. People do sometimes stay anonymous because they are afraid of becoming involved. I cannot decide whether demanding proof is sensible or whether it is how people talk themselves out of information they do not want.

What would you do with an anonymous accusation that contains one private detail and nothing else? Is there a way to take it seriously without making my boyfriend prove innocence against a claim too vague to answer?