Breaking heart. What would you do?

What would you do if you are completely in love with someone. It is reciprocated and deep. True love even. You both know it, but distance keeps you apart. Seemingly everything is great, connection, etc.
One day you get an inkling that something is different. The other denies anything. But then you find evidence. Yet the other stays connected as normal. Would you show the evidence? If so, how? Is it worth losing it all – The real love? Or do you stay and work it out?
Does staying mean you lose your dignity? Why would the other string you along?

The evidence is not solid, but it’s there. Proof of something going on.