If sex has never been a priority (for you) in your LT relationship, you've never been with anyone else so don't know any different, sex is okay, sometimes good but you could easily go without it and sometimes it feels a bit like a duty. Has pretty much always been like this as well as the obvious dip in a LTR. Then you develop feelings for someone else and realise that you feel strong sexual attraction towards them, you think about them sexually, etc? Can the relationship be worked on, can the sex improve? (Nothing has happened, just thoughts!)