Hey Summer:
I see the dilemma. Since he's your neighbor, it would make sense to look at the 3rd house, but then again, you wonder if he's a love mate, leading you to the seventh. I don't think it is either of these houses. Rather, I see it as the 5th house because this is the beginning of a romantic adventure (potentially).
Answer: Yes. He is interested in you.
Analysis: (This might be quick because I just awoke.) Since you are represented by the Sun, it's suitable that the Sun is placed in the house of neighbors. The Moon, as a full moon waning, had its last aspect with the Sun, which was in the 3rd house, thus this is very much oriented around your neighbor. The Moon is also moving into the eighth house, so there will be sexual emotions in the future.
Your neighbor is represented by Jupiter, which is forming a trine with your Sun, obviously a favorable circumstance with the Sun. Jupiter is in the house of friendship, another auspicious sign, showing that he is or will be a friend of yours. Your co-significator is Venus, and though it does not make any aspects with the significators, it does show the nature of the situation: romance. If there were more aspects, I would say this is written in stone, but with the trine alone, I will just say the door is clearly open for the both of you.
Summary: Overall, it is a positive outcome to your question.
I hope this helps.