???
How’s that supposed to look if she is cohabitating? She’s going to go out with the OP while living with her boyfriend? Or she’s supposed to move out of the apartment and find a new place in order to go out with the OP casually (when they’ve already dated and it wasn’t a success)?
How is this supposed to work?
There’s no specifically moral problem if she’s seeing another guy, but prudentially speaking it’s a lousy idea.
- This is a very long-standing relationship
- There would be immediate expectations of being very serious if she’s destroyed a long-standing relationship for the benefit of the OP.
- She’s cohabitating
- She and the OP have already failed at having a relationship.
There is a class of people that suddenly realizes how much they value the person they used to date when they see that person happy with somebody else.
There are other unattached women on earth–pick one of those.