It feels easy, like you already know how to be around each other. The risk is you stop choosing it.
The two of you
Leo. You feel real when you are actually seen. People see the warmth, and the person the room turns toward.
Sagittarius. You feel real when the horizon is still open. People see the range, and the person who makes a bigger story believable.
What wears it out
Being ignored drains you. Polite affection that never becomes admiration does too.
A small life with the door shut drains you. So does being managed for your own good.
Leo runs hot and wants it now and does not like to be moved once settled. Sagittarius runs hot and wants it now and adapts quickly, and may not finish.
Wanting each other is not the hard part. Staying awake to each other is. Comfort can turn into taking the warmth for granted. Together, it shows up as romance, play, and being admired. The other way around, it shows up as the bigger plan, farther away.
This is the answer people want before anyone knows a birth time. Two real people have more than a sun sign. If it matters, cast both charts.