There is even more to it. The relationship also has the side of Triss.
Now, forgive me, but I do not know much about Triss in the books before Times of Contempt. I know that she was involved in the early stages of Ciri's education at Kaer Morhen. That Triss was infatuated with Geralt and jealous of Yennefer's relationship with him. That she had sex with him one time, using magic to get him into her bed. That, on the journey to Kaer Morhen, she had a bout of diarrhea and Geralt had to help her with latrine business, and that she became more infatuated in the process of that. And that she finally admitted in Kaer Morhen that she was not experienced or talented enough to be in charge of Ciri's magical education, so Yennefer was called in.
While I am not sure of the order of these details, they give me a picture of a (relatively) young, talented but inexperienced sorceress, who's insecure but gets along well. Contact with Geralt, however, turns her manipulative (seducing with magic) and helpless (a talented magic healer like Triss really has no cure for diarrhea?)
I will now look at her development from books and games which I am more familiar with than with the previous tidbits.
In the books, starting at Time of Contempt, she was obviously not in a relationship with Geralt. She used her time by herself to advance in the ranks of the mages, until she actually was invited by Philippa to be part of the lodge - that secret organization consisting of what Phil thought to be the greatest and most talented sorceresses in existence. Now while she may or may not have ended up in there only because she had a relationship with Phil at the time - Triss apparently did well for herself on her own. She had a career, friends, power. Split off from Geralt, she actually did grow so much in power that she manifested that "Merigold's Hailstorm" at the progrom of Rivia that became famous later on.
This state continued during Geralt's absence. She became an esteemed advisor of King Foltest, solidly involved in the Lodge still, accepted and respected by the witchers of the wolf school, powerful enough to clearly contribute at the battle against the Salamandras at TW1's start in Kaer Morhen.
However, now that Geralt was back and that they had contact, things began to go downhill again. Her desire to show off her power against Azar Javed failed, and she was back to requiring help - which Geralt was of course glad to provide, yet again. It really spirals downhill from there. When she's finally in a pseudo-marriage "family" with Geralt, as the custodian of Alvin, she apparently can't even recall that she is actually a sorceress when the Salamandras kidnap him from out of Triss' own house. She tries to fight for him by kicking them and by screaming, not with magic. Formidable effort of course... but why didn't she just blast them with her lightning based magic spells from TW1's prologue?
It gets even worse in TW2. Triss casts a protective sphere against arrows (her cloud of butterflies) and instantly passes out. That was about her only magical contribution in TW2, except for the attempt in the elven bath (if resisting there, Geralt gets magical resistance, so there was magic seduction involved again). She spends the rest of this game in a damsel in distress position, despite the odd fact that her shackles didn't even look like made of dimeritium in the Nilfgardian camp.
The pattern of "helpless and kind of stupid while in contact with Geralt; powerful if not in contact with Geralt" is even more clear in TW3.
At the start of TW3, Triss had established a nice existence for herself in the heart of the wealthy center of Novigrad, an expensive house right at Hierarch Square. Then of course, the witch hunt starts and she has to go into hiding - even while doing that, she does great for herself though. She is the leader of that group of mages, the one who keeps them under protection of the King of Beggars. She is the one who does the negotiating with their protector. Even in hding, she is still strong. Yes, she has swapped from lightning to the instable element of fire, but she is still doing fine for herself.
Enter Geralt.
Immediately in the granary, you can notice that her spells against the witchhunters don't actually do anything at all except being very theatric. She is back to relying totally on Geralt to help her. Her behaviour during A Matter of Life and Death cannot be called sensible or intelligent by anyone - taking off the mask while people are nearby, getting drunk and that ridiculous attempt to get a kiss... all while there were clearly witnesses and witchhunters nearby. Yeah, sure.
This continues quite extremely until one vitally important point: Refusing her to help at the start of Now or Never. During Now or Never, if played as a helpful Geralt who of course wouldn't refuse to help Triss in that situation, either the Innkeep of the Kingfisher, Olivier, or one or both of the mages, Anise and Bernard, will die. However, if you refuse to help Triss at this point, Triss will somehow manage to do this part of the quest with keeping all three of these alive. You can witness that by later going to the Kingfisher; the quest's progress halts there for you. Olivier will greet you and open the door to the hiding place. And in the hiding place, Bernard and Anise will be. All alive and well. Triss did well on her own. Much better than in teamwork with Geralt.
And then at Kaer Morhen, her magical abilites have grown once again. I can easily explain this in my playthroughs by the fact that she is now clearly not in a relationship with Geralt anymore. The playthroughs of others might change the view on this, but there is also the sudden bout of jealousy (because of the kiss Yennefer gave Geralt) that might have given her this sudden and rather unexpected boost maybe.
So, the general pattern is this:
Triss is in contact / in hope to get a relationship with Geralt => Triss falls into a "helpless little girl who needs a protector" role
Triss by herself => Triss does great
A relationship under this angle does also not look quite "healthy" at all to me.