There are times when you think about OM, and times when you enjoy good thoughts about your husband.
Try to take note of what you are DOING in each of these scenarios. If you think about OM when you are gardening for example, stay OUT of the GARDEN. Oftentimes our environment and what we do in that environment trigger our thoughts. Find out what the triggers are and punch the ones you want punched, avoid the ones you want to avoid.
As for the phone number, your husband is likley just feeling sad and can't make a good decision. Similar to being drunk and needing someone to make your choices for you, sad, lonely people sometimes dont make the best choices for thesmelves either. I would argue in some cases this is how affairs start. Someone's miserable and the person they select as their designated driver decides to hand them another drink instead of driving them home.
I am thinking the number change would be a good thing for both of you. Don't leave things to his decision all the time, talk with him, dont just DO it without talking to him. But try to help him get there with a new number, don't take his first mumbled no for an answer.
Is he being emphatic about the number or is he just kinda wandering about the topic and waving it off? He MAY not realise how much it will help and is just thinking it is a waste of time.
If the new number would UPSET him then I would leave it alone, but if he's just saying no because of the hassle and him feeling hopeless that it would help, I would keep asking for a new number . Push it if you think it will help him get there, but don't push it if it will upset him.