So the "someone else" is another woman he might be seeing.
Which is probably irrelevant isn't it, if he isn't interested in the querent?
He as mercury is in your 11th house, and approaches a sextile to your co-ruler Neptune on the ascendent, so he should be open to being friends. Just friends.
The other co-ruler is Jupiter, as Ilene wrote in your 12th house of self undoing, hidden motives. Moon is separating from an opposition to this Jupiter, so this is why the situation is moving on, away from you.
Moon is appropriately in your 6th house of the work place, and approaches a trine to sun, ruler of the 6th. So being just friends is actually something positive for you and your reputation (sun in 10th).
When moon squares mars in his 3rd, try to avoid arguing with him.
Mars is in Jupiter's sign, so this repeats the Thieme of moon separating from you in your 12th.
Mercury in Capricorn approaching a conjunction with pluto is work-minded and concentrating on earnings, not love!