Ah, but he can't have another girlfriend because Eve is already his girlfriend. But, he doesn't have a boyfriend yet so he can have a Moriarty, ya know, as a treat. 😉
You know, this comment made me laugh so much that I've been sitting on it for several days until I could come up for a fanfic idea for it...in which Nicole has developed a friendship with Eve and Eve in good courtesy told her about the relationship shortly after it started and she's half cool with it (I say half because she mistakenly assumed Moriarty the fictional looks like a more sinister Jenkinseque character before she actually sees him and does not entirely get why Flynn would realize bisexuality over an old man) but Flynn got sidetracked and never bought it up to Nicole and is super freaked out when she ends up seeing him in public with Moriarty and ends up using an excuse similar to your comment except worded differently while in a panic.