Rather than a confrontation, you can make it an inquiry. He may become defensive otherwise. It would be better to speak about this face to face when he is back. Meanwhile, you may say something like- I've noticed a phone # XXXXX don't recognize and was wondering what is it all about. Based on how he responds to that, you'd know how to continue with the conversation.
You're alreaady suspecting that something may be going on correct?
Has there been prior infidelity concerns or situations?
The way you could approach this can be from his stand point. Naturally, he'd feel entitled to his privacy. Yet, you can let him know that as his partner, you're finding this behavior a bit odd and you're wondering if perhaps he's having a problem of sorts that he may talk to you about.
While he is away, it may be better just ot inquire and then wait for him to be back to delve into this deeper.
There have been other situations, but with less prove, so to speak..... this one can not be denied.
Before you consider it a romantic involvement, let him have some opportunity to elaborate.
It could be a codependent platonic relationship or anything else.
For the time being, try to treat the situation objectively. He has to answer to his behavior sooner or later.
You could see how he behaves when he is back. That way, you'd have some more examples to speak to him about that you find strange.
Otherwise, he may say that you're imagining things or become withdrawn and/or angry.
well in the note she responded that offering marriage and kids was a little bit too quick....they have to know each other better first. I am smart enough that men like to collect phone numbers, especially when they getting in their forties, but this sounds like soliciting
Of course, you're not in charge of how he reacts or what he feels. These are his own choices.
Is this a note you read then? You have seen more than calls/texts back and forth?
I have found the note, yes....written on tissue
Then that is something you can show him and ask him to explain. That is a concrete evidence at least like you said of soliciting if nothing else. You can give him the benefit of the doubt initially until you see how he responds to you.
It would be fair to let him know that it makes you uncomfortable.
I have too confront him, and the problem is that I am not confrontational at all. I will go in silence mode.
While he is away, you can't know what he's doing 24/7. When he's at home, that would be more evident. It's a situation that would need to be handled face to face as it may take more than one conversation about it.
I agree, that is my first thought as well, also I do not want to discuss this with others before speaking to him.
This is a family matter and has to be handled as such.
You'd just have to find courage to deal with your emotions meanwhile.
Waiting can be anxiety provoking
That is the hard part, but I will deal with it. Thank you for your help!