The sun moves above the earth, from east to west, on a daily basis.  Because it's smaller, it does not give light in all directions, but is more focused, like a spotlight.  Thus when it's spotlight turns, and as it physically moves away from us, it has the appearance of "setting".

And when it gets all the way west, how does it get back east again?

I have always understood Catholicism to accept that some people are neither called to marriage nor to the religious life, but to live a single life as a lay person, possibly without ever being able to discern the reason why.  And remaining single always gives you the option of pursuing either other state, if such a calling would come at any time in life.  Other states of life don’t give you that freedom.

I have trouble understanding the statement:

"Moreover, in my opinion something like two out of every three New Masses are already invalid, because the priests no longer believe in the Real Presence of Christ"

Does the priest have to believe in the real presence?

Yes, you are correct, and I've long objected to this spin on the NOM validity question.

Indeed, the priest only has to have the intention to do what the Church does, not to intend what the Church intends.

I guess the argument goes like this, though it's never been properly articulated.  In the Tridentine Rite, the intention for the Holy Sacrifice is clear, and so in that case a priest who intends to do what the Church does thereby, via some transitive connection, implicitly intends the Holy Sacrifice.  Meanwhile, in the NOM, the intention of the Rite itself is ambiguous, so it somehow has to be "supplied" by the active intention of the priest to intend the Holy Sacrifice of the Mass.  So the principle here appears to be that with the NOM, the priest's must intend to do what the Church has Traditionally intended by the Mass in order to supply the absence of this intention of the Rite.  This is extremely novel, and IMO a bunch of nonsense.  If you read Pope Leo XIII on the Anglican Orders, there's no indication there whatsoever that the defective intention of the Rite could be somehow supplied for by the intention of the priest.  He declared them simply invalid.  Period.  He did not equivocate about, well, if the minister intended to do what the Church intends by Holy Orders, it could be valid.  He just declared them invalid due to the defective intention of the Rite.  He did not say that each individual case must be investigated, to determine what the minister intended when performing the Ordination.

So you are correct that this approach to the validity of the NOM is completely novel and contrary to Traditional Catholic sacramental theology.

Nor does it take into account the problem with the validity of the Orders of the priest offering them.  If there's positive doubt about the validity of the Holy Orders, which there has to be if Bishop Williamson conditionally consecrated +Vigano (who was "consecrated" originally by Wojtyla the Great himself), then all NOMs must be presumed invalid in the practical order and therefore no one an licitly approach to receive Holy Communion at the NOM (contrary to his infamous advice to the one lady that created an uproar).  Either there is a positive doubt or there isn't.  If there is, the NOM "Sacraments" must be avoided (teaching of the Church).  If there isn't, it's not licit to conditionally ordain or consecrate.  It's really that simple.  But even Bishop Williamson and the pre- +Fellay SSPX have long muddied the waters.

Of course, how can anyone "investigate" whether the priest had the right "internal intention" anyway, since that's knowable only in the internal forum?

SSPX approach to the validity of the NOM "Sacraments" has long been a hot mess.  While Bishop Williamson rightly points out that SSPX have refused to consider the possibility they might be invalid for political reasons, it's also true that the SSPX have engaged historically in the same refusal to consider them objectively in positive doubt due to also to the political reason of constantly having to fend off the evil specter that is sedevacantism.

Saint Dominique...you are being very wise to not pursue marriage at this time in your life.  It's clear you aren't interested in being a wife right now and God has not presented anyone appealing to you.  Many traditional priests will confirm that young men today are effeminate compared to earlier generations.  I think they have high levels of estrogen from tainted food (evidence is "manboobs") that cause them to be unmotivated to excel at anything, whether it's their career or appearance.  I also wonder if homeschooling has made many young men passive because of lack of competition.  I have 3 sons so I see the difference between the older one who went to school v the younger ones who I homeschooled.  

When you do meet someone you are attracted to, you will feel differently.

Also, can we please stop the idea that it’s vain to take care of your appearance? NONE of the guys at my parish are interested or even have the care to work out or be fit. So in conclusion, stop trying to rush young Catholics into decisions that are life-changing, please...

OK, well, that may be your "parish" (aka "chapel"), but it's not universally true.  As for it being "vain" to care for your appearance, it can be or it can't be.  Depends on the individual and depends on whether or not it's "disordered", i.e. not in its proper place and proportion and for the right motivations.  So that statement is neither here nor there.  Not to mention that being "fit" and looking good are not necessarily tied together or motivated by the same things.  You can want to be fit so you can better perform your duties of state (properly ordered) and look good out of respect for your future spouse (or to expand your options for your future spouse).  So, whether or not it's "vain" and disproportionate and not properly ordered to higher things depends entirely on the individual.  You can't make a blanket statement along those lines.  Basically, for a man to be excessively concerned about his "appearance" (for the sake of looks) would be suspect in terms of his overall masculinity.  This doesn't mean being slovenly either, but if someone's constantly primping in a mirror, almost as much as a girl/woman might, there's a red flag there.

So, reading between all the lines, with everything you've said, I get the impression that someone (perhaps SSPX clergy) are pushing you to date some guys that you're not attracted to at the chapel, in the interests of playing matchmaker.  Big deal.  Just say no.