In addition to Pellissier's suggestions, you might want to look into:
Unlicensed:
Canvas 2 ~ Niji-iro no Sketch ~ -- This series is still ongoing, so I cannot promise a happy ending. Fairly lighthearted with some drama involved, but the angst level has mostly been low thus far.
Lamune -- Very sweet romance with strong emphasis on the relationship of the two main characters. This show is not for everyone - it moves at a very relaxed pace and the focus is on day-to-day life, so I do not recommend it if you want a lot of action mixed in with the romance.
Natsuiro no Sunadokei -- This one is a short, two-episode series that mixes time travel and romance. Interesting story line and pretty animation, plus features an amazing VA cast. Bit of advice: if you dislike harem anime, do not let all the girls shown in the opening fool you into thinking this show will be one; there is only a single love interest.
Licensed:
Ah! My Goddess -- Belldandy. Need I say more?
