Being in "Reviewer invited" state for 3 months, What could it say?
It means the editor(s) invited reviewers who have not accepted the invitation. If this status has remained the same for 3 months, it's not a good sign. Completing the review can take time, but agreeing to review should be much faster.

My guess is that the editor is either very busy or not very active. He/she invited reviewers and left the manuscript alone. Now would be a good time to nudge the editor and hint that they should be inviting new reviewers, since the currently-invited ones are not likely to agree to review.