せっかく

せっかくsekkakuneutral

savor + (past) + after all that trouble — the cost gets wasted or cashed in

sekkaku ajiwatta noni

after all that trouble — the cost gets wasted or cashed in

meaning: even though I went to the trouble of savoring

せっかく味あじわったのに、当日とうじつは大雨おおあめだった。

sekkaku ajiwatta noni, toujitsu wa ooame datta.

It poured with rain on the day, even though I went to the trouble of savoring. neutral

せっかく京都きょうとまで来きたのだから、一泊いっぱくしていこう。

sekkaku kyouto made kita no da kara, ippaku shite ikou.

Since we've come all the way to Kyoto, let's stay the night. neutral

All examples5

after going to the trouble — the cost, then reported wasted

せっかく予約よやくしたのに、当日とうじつは大雨おおあめだった。
sekkaku yoyakushita noni, toujitsu wa ooame datta.
It poured with rain on the day, even though I went to the trouble of booking. neutral
せっかくの休やすみなのに、朝あさから雨あめだ。
sekkaku no yasumi na noni, asa kara ame da.
A precious day off, and it's been raining since morning. casual
せっかく作つくってくれたのに、残のこしてしまってごめん。
sekkaku tsukutte kureta noni, nokoshite shimatte gomen.
You went to the trouble of making it and I left some — sorry. casual

since the chance is here — the cost cashed in instead

せっかく京都きょうとまで来きたのだから、一泊いっぱくしていこう。
sekkaku kyouto made kita no da kara, ippaku shite ikou.
Since we've come all the way to Kyoto, let's stay the night. neutral
せっかくご用意よういいただいたのですから、ありがたく頂戴ちょうだいいたします。
sekkaku go youi itadaita no desu kara, arigataku choudai itashimasu.
Since you have gone to the trouble of preparing it, I will gratefully accept. formal

せっかくだからsekkakudakaracolloquial
frozen, with nothing of its own; means "while we're at it, make it count." せっかくですから is the polite shop or office version.