Which proves that Lyanna Stark loved Rhaegar

"How would J and Daenerys be related if R + L = J?"

Jon would be Daenerys' nephew.

Since Rhaegar Targaryen is Dany's older brother, both are children of Aerys and Rhaella Targaryen and

Jon is Rhaegars' (possibly) illegitimate son (of Lyanna Stark), Dany is Jon's aunt.

Your family tree is at the bottom of this page.

To update

According to this recently released character association table, HBO has confirmed that Jon is Lyanna and Rhaegars' son. It also confirms that (on the show at least) Rhaegar kidnapped Lyanna, meaning Jon is out of wedlock.

Update for season 7:

Jon has been revealed to be the trueborn son of Rhaegar and Lyanna. Rhaegar didn't kidnap Lyanna, he loved her and she loved him back. Rhaegar had his marriage to Elia Martell annulled and instead married Lyanna. Jon's mother called him "Aegon Targaryen" on her deathbed.

Möoz

Why stop there? They are actually aunt-nephew, cousins, second cousins, again Cousins ​​and again second cousins. This is because Dany and Rhaegar are so heavily bred. In fact, Dany and Jon seem to share roughly 44% of their DNA; so genetically they are basically siblings !!

Sudhanva

Now explain your relationships with your (future) children.

Flater

The fact that the table shows that Rhaegar is Jon's father, but also kidnaps Rhaegar Lyanna (which has now been proven wrong) means that there must have been a point in time when Rhaegar was known to be Jon's father but his marriage to Lyanna has not yet been revealed. From this you can conclude that for S06E10, HBO intended to confirm Rhaegar as the father as well, as this is the only time we are told anything about Jon's parentage before the marriage itself is also featured in S07E07 (or the "Regger" scene in S07E05) is revealed. which in turn would confirm the marriage itself)