My child seems to have no friends, but if they seem happy, is that a problem?

Even if your child spends a lot of time alone, if they feel safe and are enjoying themselves, that in itself is not a problem. Friendship is less about "how many" than about quality—whether there is even one person they can comfortably be with. Still, watch for signs that they actually want to join in but don't know how, or that they are being left out or teased. Ask the teacher specifically whether your child is isolated during breaks or group activities. If they seem to want connection, help bridge it through small, short activities built around a shared interest.