Lasting relationships are built on trust. Trust is built on honesty. Honesty isn't hard and it's a good habit. Bite the bullet, tell the truth. Telling the truth is easier than lying, all rumor and myth to the contrary.
Lies are a lot of work.
They weigh you down and isolate you. Small lies get lonely and seek out bigger lies. Don't ask one lover to lie or keep secrets from others. Secrets build walls and discourage intimacy. Know the difference between privacy and secrecy.