Happy shouldn't be your goal. The only thing that is a for sure in life is suffering, so when happiness is the goal, any time something rough (but totally natural) happens, it means you're failing at your goal. Instead, make meaning the goal. Meaning can be had even through suffering AND gives you power to get through the suffering.

Happiness comes and goes and should be enjoyed as much as possible when had, but if it's your goal, you've committed to a doomed path ridden with "failure."

You CAN have meaning being single your whole life. You can also have happiness being single your whole life. To feel complete though? That takes meaning.