Looking for dramas or movies where they gay characters are the main leads and it ends happily for them. 

Where your eyes linger, 2wish, 2gether and until we meet again. You can watch on You tube.

Subscribing because I'd also like to watch more of this genre.

From my limited experience: HIStory3: Trapped for MLM (I'd say the chemistry was medium) and Out of Breath for WLW romance. Out of Breath is very short / quick (which also means limited skinship), very realistic, and extremely cute. 

Since you're watching The Untamed, I'd also recommend reading the novel.

Love by Chance-This depends on whether you liked the main or second couple more. My fave is the lead couple so I liked it. There's S2 coming just in case you aren't satisfied with the ending.  It's worth it, the leads have awesome chemistry together and do an excellent job even if these were their first roles in BL. 

Where Your Eyes Linger

2gether the series

History 3: Trapped

History3: Trapped 

Why R U

Tharntype

I second 'TharnType'. The chemistry between the leads was just AMAZING. Another good one is, SOTUS.....this one release a few years back but was a massive hit both in Thailand and Internationally. 

I really reccomend The Untamed,it's  not outspokenly gay, but it's a Chinese BL that got censored. Really good energy between the leads and a happy ending for them!

Theory of Love

Dark Blue Kiss

Dark Blue and Moonlight

My Engineer

2 Moons

Lovesick

Do a search using 'gay' tag

I watch a lot of LGTBQ dramas and movies, check my stats, click the 'gay character' tag  (has #63) and it will take to to a whole list of dramas and movies with gay tag, can't be sure of happy endings other than what people posted in response to your inquiry :-)

Dark Blue Kiss

Sotus, Sotus S

Love By Chance

Theory of Love

HIStory 3: Trapped

Im surprised nobody recommended Ossan's love yet. Try this one. It's highly recommended!