Solitary organisms might not be able to feel loneliness as we humans interpret it. However, come breeding season, their hormones will kick in and they will produce a desire to find a mate and procreate. Sometimes that includes all kinds of social behaviors to include calling, displays, and even deadly aggressiveness to competing males.

Your toad is fine and will will a long live alone. But; if you want (and the toads are similar sized and tolerant) can keep 2 or more as long as the enclosure is big enough for all. Good luck !