As previously stated, Rune is a big flirt and also a bit of a horndog, and he doesn't really care if someone sees/interrupts him when getting frisky. Lack of self-awareness or maybe he enjoys putting on a bit of a show? Who knows.
Sigil however is quite the opposite, and gets extremely flustered at the mere THOUGHT that someone might see them.
It's definitely happened more than once that Rune decides to bully his timid boyfriend by pushing him down right in the lounge area of home base, enjoying the following struggle and embarrassment.