As a counterpoint to your experiences, accepting invitations despite not feeling like going out works very well for me - at times when I'm feeling loneliness (o

As a counterpoint to your experiences, accepting invitations despite not feeling like going out works very well for me - at times when I'm feeling loneliness (or its onset) I almost always find that forcing myself to accept an invitation gives positive results. Perhaps as suggested by another commentator here, the concept of loneliness is nuanced - e.g. you were looking for deep connections whereas usually I just want some fun companionship, or something like that.