Q: My 21-year-old son who lives with me broke up with his girlfriend of two years. This was not a mutual split. He has found another and moved on. I understand, but I dearly miss the first girl. She was part of our family and I feel like I've lost a child.

I would like to stay in touch. My son says he doesn't care. I don't want to encourage her toward my son. He's done with her. What's good ex-etiquette?

A: Your problem is no different than any "in-law" faces when their child breaks up with someone. You get attached, they are not around anymore, and you miss them.

As you might expect, I'm an advocate of staying in touch with past partners, but that is based on the best interest of the children produced from the relationship. Then you are grandma staying in touch with your grandchildren's mother or father. When there are no children, you really have to do some soul-searching.

First, you said the breakup was not mutual. Therefore, your ongoing relationship with your child's former partner may give her false hope of getting back together with your son. It's a connection.

Your conversations will inevitably include him — she'll know what he's doing, where he might be, follow him on Facebook through being friends with you, etc. That will keep him forefront in her mind and if she really does want to get over him, your presence will make that more difficult — at least for now. If she harbors a not-so-secret desire to get back together, how much she knows about him could get kind of creepy.

Second, now that your son has moved on, you probably will want to bond with the new girlfriend. She may perceive you as a "traitor" for encouraging a relationship with her boyfriend's past girlfriend. "You like her better — I don't like you."

New girlfriend doesn't like mom equals new girlfriend and son will not be around much. Your son lives with you. If you want that to continue — perhaps he's going to college and it's a necessity — it's not a good idea to alienate the girlfriend. He will end up living with the girlfriend, his schooling might suffer and you will definitely not see him as often as you like.

So, this all boils down to: Tread softly in the past.

Be honest and straightforward. Don't try to secretly maintain the old relationship while cultivating the new. Someone will find out and you will look like a traitor.

If you do talk to the old girlfriend, be honest. "I love you and miss you, but I think it is best we let some time pass before we speak on a regular basis."

And then watch how your son's new relationship progresses. When all is said and done, your allegiance lies with your son, and as long as he's being straight with both women, that's whose lead you follow.