Adult Contemporary Romance. Wife leaves husband, but they are not divorced. She thinks he doesn't know where she is. He surprises her at a work party. Read around late 1980s/early 1990s.

[Oracld271]

I am not sure, but I believe that the husband was keeping track of her and showed up because he thinks she is starting to date someone in her company.

Sorry, I am unsure what country it was set in, but my impression is that it was the US.

[Lobstergirl, au gratin]

Oracld271, are you still looking for this or did you find it?

[Oracld271]

Yes. Still looking.

[Kris]

Oracld271, what are the main characters' jobs?

Is this a second chance romance? Or love triangle?

What's the mood - e.g., romantic, suspense, angsty, steam/clean, funny at times?

[Oracld271]

I just don't remember that much about it.

It was most likely a Harlequin, so not super steamy.
The husband has come back into her life to get her back. The wife had been dating the boss/coworker but it had just started and was not serious.

I don't know the wife's exact job, but I have the impression that it was office work.

[Oracld271]

I just remembered, I believe that the husband 'blackmails' the wife. Her employer doesn't know she is married and the husband agrees not to tell if she agrees to date him.

[Liz]

Following